Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#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 fs first
#define sc second
typedef vector<ll> vl;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<tuple<ll,ll>> vtl;
typedef pair<ll, ll> l_l;
#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))

void solve(){
    //abc96c
    int h,w;
    cin>>h>>w;
    string board[60][60];
    rep(i,h){
      rep(j,w){
        cin>>board[i][j];
      }
    }
    int dx[]={1,0,-1,0};
    int dy[]={0,1,0,-1};
    bool f=0;
    int cnt=0;
    rep(i,h){
        rep(j,w){
            if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
        }
    }
    if(h==1&&w==1&&board[0][0]=='#'){
        cout<<"Yes"<<endl;
        return;
    }
    cout<<(cnt==0?"Yes":"No")<<endl;
}

int main(){
    cout<<std::fixed<<std::setprecision(10);
    ios::sync_with_stdio(false);
    cin.tie(0);
    solve();
}

Compiler output:
a.cc: In function 'void solve()':
a.cc:34:29: error: no match for 'operator==' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'char')
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                 ~~~~~~~~~~~ ^~ ~~~
      |                           |    |
      |                           |    char
      |                           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,
                 from a.cc:1:
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'char'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::pair<_T1, _T2>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |                                ^~~
/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:34:32: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   34 |             if (board[i][j] == '#' && board[i][j - 1] != '#' && board[i - 1][j] != '#' && board[i][j + 1] != '#' && board[i + 1][j] != '#') cnt++;
      |