Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
string s;
  cin >> s;
  int ans,i,size;
  s=s.size();
  ans=0;
  
  for(i=0;i<s/2;++i)
  {
  if(s.at(i)!=s.at(s-1-i)) ans++;
  }

  cout << ans;
return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:14: error: no match for 'operator/' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   11 |   for(i=0;i<s/2;++i)
      |             ~^~
      |             | |
      |             | int
      |             std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/complex:430:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const complex<_Tp>&)'
  430 |     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:430:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/complex:439:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const _Tp&)'
  439 |     operator/(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:439:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/complex:448:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const complex<_Tp>&)'
  448 |     operator/(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:448:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   11 |   for(i=0;i<s/2;++i)
      |               ^
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   11 |   for(i=0;i<s/2;++i)
      |               ^
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:11:15: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   11 |   for(i=0;i<s/2;++i)
      |               ^
a.cc:13:21: error: no match for 'operator-' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   13 |   if(s.at(i)!=s.at(s-1-i)) ans++;
      |                    ~^~
      |                    | |
      |                    | int
      |                    std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_iterator.h:618:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__y.base() - __x.base())) std::operator-(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  618 |     operator-(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:618:5: note:   template argument deduction/substitution failed:
a.cc:13:22: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   13 |   if(s.at(i)!=s.at(s-1-i)) ans++;
      |                      ^
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr decltype ((__x.base() - __y.base())) std::operator-(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1790 |     operator-(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1790:5: note:   template argument deduction/substitution failed:
a.cc:13:22: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   13 |   if(s.at(i)!=s.at(s-1-i)) ans++;
      |                      ^
/usr/include/c++/14/complex:370:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator-(const complex<_Tp>&, const complex<_Tp>&)'
  370 |     operator-(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:370:5: note:   template argument deduction/substitution failed:
a.cc:13:22: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
   13 |   if(s.at(i)!=s.at(s-1-i)) ans++;
      |                      ^
/usr/include/c++/14/complex:379:5