Language: C++

#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
#include <climits>
#include <cmath>
#include <functional>
#include <map>
#include <queue>
#include <set>

#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define INF 999999999
#define size_t unsigned long long
#define ll long long
#define rep(i,a) for(int i=0;i<(a);i++)
#define repr(i,a) for(int i=(int)(a)-1;i>=0;i--)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define FORR(i,a,b) for(int i=(int)(b)-1;i>=a;i--)
#define ALL(a) a.begin(), a.end()
using namespace std;
int si() { int x; scanf("%d", &x); return x; }
long long sl() { long long x; scanf("%lld", &x); return x; }
string ss() { string x; cin >> x; return x; }
void pi(int x) { printf("%d ", x); }
void pl(long long x) { printf("%lld ", x); }
void pd(double x) { printf("%.15f ", x); }
void ps(const string &s) { printf("%s ", s.c_str()); }
void br() { putchar('\n'); }

const int MOD = 1e9 + 7;

struct mint {
    int n;
    mint(int n_ = 0) : n(n_) {}
};

mint operator+(mint a, mint b) { a.n += b.n; if (a.n >= MOD) a.n -= MOD; return a; }
mint operator-(mint a, mint b) { a.n -= b.n; if (a.n < 0) a.n += MOD; return a; }
mint operator*(mint a, mint b) { return (long long)a.n * b.n % MOD; }
mint &operator+=(mint &a, mint b) { return a = a + b; }
mint &operator-=(mint &a, mint b) { return a = a - b; }
mint &operator*=(mint &a, mint b) { return a = a * b; }
int a[50];
int count;

int main () {
  string s;
  cin >> s;
  rep(i,4) a[s[i] - 'A']++;
  rep(i,40) if(a[i] == 2) count++;
  if(count == 2) s = "Yes";
  else s = "No";
  cout << s << endl; 
}


Compiler output:
a.cc: In function 'int main()':
a.cc:53:27: error: reference to 'count' is ambiguous
   53 |   rep(i,40) if(a[i] == 2) count++;
      |                           ^~~~~
In file included from /usr/include/c++/14/algorithm:86,
                 from a.cc:2:
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:47:5: note:                 'int count'
   47 | int count;
      |     ^~~~~
a.cc:54:6: error: reference to 'count' is ambiguous
   54 |   if(count == 2) s = "Yes";
      |      ^~~~~
/usr/include/c++/14/pstl/glue_algorithm_defs.h:101:1: note: candidates are: 'template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)'
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/14/bits/stl_algo.h:4025:5: note:                 'template<class _IIter, class _Tp> typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)'
 4025 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
a.cc:47:5: note:                 'int count'
   47 | int count;
      |     ^~~~~