/in/foo.cc: In function 'long long unsigned int crt(int, int)':
/in/foo.cc:26:9: error: reference to 'hash' is ambiguous
  return hash[tail]-hash[head-1]*pw[tail-head+1];
         ^~~~
/in/foo.cc:10:5: note: candidates are: long long unsigned int hash [200010]
 ull hash[200010],pw[200010],hash2[200010];
     ^~~~
In file included from /usr/include/c++/6/bits/basic_string.h:5643:0,
                 from /usr/include/c++/6/string:52,
                 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:3:
/usr/include/c++/6/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^~~~
/in/foo.cc:26:20: error: reference to 'hash' is ambiguous
  return hash[tail]-hash[head-1]*pw[tail-head+1];
                    ^~~~
/in/foo.cc:10:5: note: candidates are: long long unsigned int hash [200010]
 ull hash[200010],pw[200010],hash2[200010];
     ^~~~
In file included from /usr/include/c++/6/bits/basic_string.h:5643:0,
                 from /usr/include/c++/6/string:52,
                 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:3:
/usr/include/c++/6/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:40:3: error: reference to 'hash' is ambiguous
   hash[i]=hash[i-1]*P+a[i];
   ^~~~
/in/foo.cc:10:5: note: candidates are: long long unsigned int hash [200010]
 ull hash[200010],pw[200010],hash2[200010];
     ^~~~
In file included from /usr/include/c++/6/bits/basic_string.h:5643:0,
                 from /usr/include/c++/6/string:52,
                 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:3:
/usr/include/c++/6/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^~~~
/in/foo.cc:40:11: error: reference to 'hash' is ambiguous
   hash[i]=hash[i-1]*P+a[i];
           ^~~~
/in/foo.cc:10:5: note: candidates are: long long unsigned int hash [200010]
 ull hash[200010],pw[200010],hash2[200010];
     ^~~~
In file included from /usr/include/c++/6/bits/basic_string.h:5643:0,
                 from /usr/include/c++/6/string:52,
                 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:3:
/usr/include/c++/6/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^~~~