/in/foo.cc: In function 'int main()':
/in/foo.cc:66:25: error: no match for 'operator!=' (operand types are 'Num' and 'long int')
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                         ^
In file included from /usr/include/c++/6/iosfwd:40:0,
                 from /usr/include/c++/6/ios:38,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/postypes.h:221:5: note: candidate: template<class _StateT> bool std::operator!=(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
     ^~~~~~~~
/usr/include/c++/6/bits/postypes.h:221:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::fpos<_StateT>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_pair.h:448:5: note: candidate: template<class _T1, class _T2> constexpr bool std::operator!=(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_pair.h:448:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::pair<_T1, _T2>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:304:5: note: candidate: template<class _Iterator> bool std::operator!=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
     operator!=(const reverse_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:304:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::reverse_iterator<_Iterator>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:361:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator!=(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator!=(const reverse_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:361:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::reverse_iterator<_Iterator>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:1125:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator!=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)
     operator!=(const move_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1125:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::move_iterator<_IteratorL>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:1131:5: note: candidate: template<class _Iterator> bool std::operator!=(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&)
     operator!=(const move_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1131:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::move_iterator<_IteratorL>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/string:41:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/allocator.h:158:5: note: candidate: template<class _T1, class _T2> bool std::operator!=(const std::allocator<_CharT>&, const std::allocator<_T2>&)
     operator!=(const allocator<_T1>&, const allocator<_T2>&)
     ^~~~~~~~
/usr/include/c++/6/bits/allocator.h:158:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::allocator<_CharT>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/string:41:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/allocator.h:164:5: note: candidate: template<class _Tp> bool std::operator!=(const std::allocator<_CharT>&, const std::allocator<_CharT>&)
     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
     ^~~~~~~~
/usr/include/c++/6/bits/allocator.h:164:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/string.h:32:0,
                 from /in/foo.cc:3:
/in/foo.cc:66:27: note:   'Num' is not derived from 'const std::allocator<_CharT>'
   while((t=mult1(tn,t,k)!=NULL)&&(t.s[i]!=n.s[i]))
                           ^
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/basic_string.h:5112:5: note: candidate: template<class _Ch