/in/foo.cc: In function 'int main()':
/in/foo.cc:50:6: error: no match for 'operator>>' (operand types are 'std::istream {aka std::basic_istream<char>}' and 'int [100]')
   cin>>a;
   ~~~^~~
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:168:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(bool& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:168:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: warning: the address of 'a' will always evaluate as 'true' [-Waddress]
   cin>>a;
        ^
/in/foo.cc:50:8: error: invalid initialization of non-const reference of type 'bool&' from an rvalue of type 'bool'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:172:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>] <near match>
       operator>>(short& __n);
       ^~~~~~~~
/usr/include/c++/6/istream:172:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'short int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(short int)((int*)(& a))' to 'short int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:175:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned short& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:175:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'short unsigned int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(short unsigned int)((int*)(& a))' to 'short unsigned int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:179:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>] <near match>
       operator>>(int& __n);
       ^~~~~~~~
/usr/include/c++/6/istream:179:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(int)((int*)(& a))' to 'int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:182:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned int& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:182:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'unsigned int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(unsigned int)((int*)(& a))' to 'unsigned int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:186:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(long& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:186:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'long int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(long int)((int*)(& a))' to 'long int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:190:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned long& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:190:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'long unsigned int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(long unsigned int)((int*)(& a))' to 'long unsigned int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:195:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(long long& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:195:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'long long int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(long long int)((int*)(& a))' to 'long long int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:199:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(unsigned long long& __n)
       ^~~~~~~~
/usr/include/c++/6/istream:199:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid conversion from 'int*' to 'long long unsigned int' [-fpermissive]
   cin>>a;
        ^
/in/foo.cc:50:8: error: cannot bind rvalue '(long long unsigned int)((int*)(& a))' to 'long long unsigned int&'
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:235:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] <near match>
       operator>>(void*& __p)
       ^~~~~~~~
/usr/include/c++/6/istream:235:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:50:8: error: invalid initialization of non-const reference of type 'void*&' from an rvalue of type 'void*'
   cin>>a;
        ^
In file included from /usr/include/c++/6/iostream:40:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/istream:120:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
       operator>>(__istream_type& (*__pf)(__istream_type&))
       ^~~~~~~~
/usr/include/c++/6/istream:120:7: note:   no known conversion for argument 1 from 'int [100]' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&