Language: C++

// #pragma GCC optimize(2)
// #pragma G++ optimize(2)
// #pragma comment(linker,"/STACK:102400000,102400000")

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

typedef long long int64;
typedef unsigned int ui;
typedef unsigned long long ull;
typedef float fl;
typedef double dl;
typedef pair<int,int> pii;
#if (WIN32) || (WIN64) || (__WIN32) || (__WIN64) || (_WIN32) || (_WIN64) || (WINDOWS)
#define lld "%I64d"
#define llu "%I64u"
#else
#define lld "%lld"
#define llu "%llu"
#endif
#define uint(n) ((unsigned int)(n))
#define int64(n) ((long long)(n))
#define ull(n) ((unsigned long long)(n))
#define fl(n) ((float)(n))
#define dl(n) ((double)(n))
#define char(n) ((char)(n))
#define Bool(n) ((bool)(n))
#define fixpoint(n) fixed<<setprecision(n)

const int INF=1061109567;
const int NINF=-1044266559;
const int64 LINF=4557430888798830399;
const dl eps=1e-15;
#define MOD (1000000007)
#define PI (3.1415926535897932384626433832795028841971)

#define MP make_pair
#define MT make_tuple
#define All(a) (a).begin(),(a).end()
#define pall(a) (a).rbegin(),(a).rend()
#define Log(x,y) log(x)/log(y)
#define SZ(a) ((int)(a).size())
#define rep(i,n) for(int i=0;i<((int)(n));i++)
#define rep1(i,n) for(int i=1;i<=((int)(n));i++)
#define repd(i,n) for(int i=((int)(n))-1;i>=0;i--)
#define repd1(i,n) for(int i=((int)(n));i>=1;i--)
#define repv(itr,v) for(__typeof((v).begin()) itr=(v).begin();itr!=(v).end();itr++)
#define repV(i,v) for(auto i:v)
#define repE(i,v) for(auto &i:v)
#define MS(x,y) memset(x,y,sizeof(x))
#define MC(x) MS(x,0)
#define MINF(x) MS(x,63)
#define MCP(x,y) memcpy(x,y,sizeof(y))
#define UN(v) sort(All(v)),v.erase(unique(All(v)),v.end())
#define filein(x) freopen(x,"r",stdin)
#define fileout(x) freopen(x,"w",stdout)
#define fileio(x)\
	freopen(x".in","r",stdin);\
	freopen(x".out","w",stdout)
#define filein2(filename,name) ifstream name(filename,ios::in)
#define fileout2(filename,name) ofstream name(filename,ios::out)
#define fileio2(filename,name) fstream name(filename,ios::in|ios::out)
#define sqr(x) ((x)*(x))
#define Pause system("pause")
#define Cls system("cls")
#define fs first
#define sc second
#define SF scanf
#define PF printf

const int maxn=INF;

int main()
{
	string s;cin>>s;
	cout<<(s.end()=='s'?s+"es":s+"s");

	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:76:23: error: no match for 'operator==' (operand types are 'std::__cxx11::basic_string<char>::iterator' and 'char')
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                ~~~~~~~^~~~~
      |                     |   |
      |                     |   char
      |                     std::__cxx11::basic_string<char>::iterator
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:5:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1199:5: 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>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1274:5: 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>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
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:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::pair<_T1, _T2>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::reverse_iterator<_Iterator>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::reverse_iterator<_Iterator>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::move_iterator<_IteratorL>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::move_iterator<_IteratorL>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::fpos<_StateT>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:76:25: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::allocator<_CharT>'
   76 |         cout<<(s.end()=='s'?s+"es":s+"s");
      |                         ^~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: note: candidate: 'template<class _CharT, class