Language: C++

#include<bits/stdc++.h>
using namespace std;

int main()
{
  string s,t,i,j,ans=0;
  
  cin >> s >> t ;
  
  for(i=0;i<=2;i++)
    if(s[i]==t[i]) ans++;
  cout << ans << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:9: error: ambiguous overload for 'operator=' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   10 |   for(i=0;i<=2;i++)
      |         ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.h:817:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  817 |       operator=(const basic_string& __str)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:828:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  828 |       operator=(const _CharT* __s)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:840:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(_CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  840 |       operator=(_CharT __c)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:858:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  858 |       operator=(basic_string&& __str)
      |       ^~~~~~~~
a.cc:10:12: error: no match for 'operator<=' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   10 |   for(i=0;i<=2;i++)
      |           ~^~~
      |           |  |
      |           |  int
      |           std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181:
/usr/include/c++/14/bits/regex.h:1154:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<=(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1154 |     operator<=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1154:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1260:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<=(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1260 |     operator<=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1260:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1353:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<=(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1353 |     operator<=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1353:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1427:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<=(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1427 |     operator<=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1427:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1521:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1521 |     operator<=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1521:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1599:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<=(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1599 |     operator<=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1599:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/regex.h:1699:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1699 |     operator<=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1699:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 |   for(i=0;i<=2;i++)
      |              ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 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_pair.h:1064:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1064 |     operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1064:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::pair<_T1, _T2>'
   10 |   for(i=0;i<=2;i++)
      |              ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:469:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  469 |     operator<=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:469:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/stl_iterator.h:513:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  513 |     operator<=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:513:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/stl_iterator.h:1704:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1704 |     operator<=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1704:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/bits/stl_iterator.h:1767:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1767 |     operator<=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1767:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   10 |   for(i=0;i<=2;i++)
      |              ^
In file included from /usr/include/c++/14/bits/basic_string.h:47:
/usr/include/c++/14/string_view:717:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<=(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  717 |     operator<=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:717:5: note:   template argument deduction/substitution failed:
a.cc:10:14: note:   'std::__cxx11::basic_string<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   10 |   for(i=0;i<=2;i++)
      |              ^
/usr/include/c++/14/string_view:724:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<=(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  724 |     opera