Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
#define ll long long int
#define pb push_back
#define mp make_pair
#define boost ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define forn(i, n) for(int i = 0; i < (int)(n); i++)
#define ford(i, n) for(int i = (int)(n) - 1; i >= 0; i--)
#define F first
#define S second
#define mset(x,v) memset(x, v, sizeof(x))
#define left(x) 2*x
#define right(x) (2*x) + 1
#define ALL(t) (t).begin(),(t).end() 
#define ret return 0
#define gcd(a,b) __gcd((a),(b))
#define lcm(a,b) ((a)*(b))/gcd((a),(b))
#define rev(s) reverse(s.begin(),s.end())
#define WL(t) while(t --)
#define MOD 1000000007
char mat[100][100];
int n,m;
int vis[100][100],dist[100][100];
int dx[] = {1,-1,0,0} , dy[] = {0,0,1,-1};
bool isok(int x,int y)
{
      if(x<0 || x>n || y<0 || y>m)
      return false;
      return mat[x][y]=='.';
}
void bfs(int x,int y)
{
      vis[x][y]=1;
      dist[x][y]=0;
      queue<pii> q1;
      q1.push({x,y});
      while(!q1.empty())
      {
            int a=q1.front().F;
            int b=q1.front().S;
            q1.pop();
            for(int i=0;i<4;i++)
            {
                  int xx=a+dx[i];
                  int yy=b+dy[i];
                  if(vis[xx][yy]==0 && isok(xx,yy))
                  {
                        if(dist[xx][yy]>dist[a][b]+1)
                        {
                              dist[xx][yy]=dist[a][b]+1;
                              vis[xx][yy]=1;
                              q1.push({xx,yy});
                        }
                  }
            }
      }
}
int main()
{
      boost;
      cin>>n>>m;
      int cnt=0;
      forn(i,n)
      {
            forn(j,m)
            {
                  cin>>mat[i][j];
                  if(mat[i][j]=='.')
                  {
                        if(i==0 && j==0)
                        continue;
                        if(i==n-1 && j==m-1)
                        continue;
                        cnt++;
                  }
            }
      }
      mset(vis,0);
      mset(dist,9);
      bfs(0,0);
      int x=dist[n-1][m-1]-1;
      cout<<abs(x-cnt)<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:83:23: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and '<unresolved overloaded function type>')
   83 |       cout<<abs(x-cnt)<endl;
      |       ~~~~~~~~~~~~~~~~^~~~~
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:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1224:5: 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>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1317:5: 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>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   couldn't deduce template parameter '_Bi_iter'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   couldn't deduce template parameter '_Bi_iter'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
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:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 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:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   couldn't deduce template parameter '_CharT'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
a.cc:83:24: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   83 |       cout<<abs(x-cnt)<endl;
      |                        ^~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Alloc