Language: C++

#include <iostream>
using namespace std;

int H, W;
int count = 0;

int main(){
    cin >> H >> W;
    const char s[H - 1][W - 1];
    for(int h = 0; h < H; h++){
        for(int w = 0; w < W; w++){
            cin >> s[h][w];
        }
    }
    if(s[0][0] == "#"){
         s[0][0] = ".";
         count++;
    }
    int h = 0, w = 0;
    while(s[h][w] != s[H - 1][W - 1]){
        if(s[h + 1][w] == "."){
            h++;
            w++;
            if(s[h][w] == "#"){
                s[h][w] == ".";
                count++;
            }
        }
        else if(s[h][w + 1] == "."){
            h++;
            w++;
            if(s[h][w] == "#"){
                s[h][w] == ".";
                count++;
            }
        }
        else{
            h++;
            s[h][w] == ".";
            count++;
            w++;
            if(s[h][w] == "#"){
                s[h][w] == ".";
                count++;
            }
        }
    }
    cout << count << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:16: error: uninitialized 'const s' [-fpermissive]
    9 |     const char s[H - 1][W - 1];
      |                ^
a.cc:12:17: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and 'const char')
   12 |             cin >> s[h][w];
      |             ~~~ ^~ ~~~~~~~
      |             |            |
      |             |            const char
      |             std::istream {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/iostream:42,
                 from a.cc:1:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'long long unsigned int&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:219:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'float&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:223:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'double&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:227:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  227 |       operator>>(long double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:227:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: cannot bind non-const lvalue reference of type 'long double&' to a value of type 'char'
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: invalid conversion from 'char' to 'void*' [-fpermissive]
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
      |                          |
      |                          char
a.cc:12:26: error: cannot bind rvalue '(void*)((long int)((char)s[h][w]))' to 'void*&'
/usr/include/c++/14/istream:122:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:122:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: invalid conversion from 'char' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'} [-fpermissive]
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
      |                          |
      |                          char
/usr/include/c++/14/istream:126:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]' (near match)
  126 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:126:7: note:   conversion of argument 1 would be ill-formed:
a.cc:12:26: error: invalid conversion from 'char' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&)' {aka 'std::basic_ios<char>& (*)(std::basic_ios<char>&)'} [-fpermissive]
   12 |             cin >> s[h][w];
      |                    ~~~~~~^
      |                          |
      |                          char
/usr/include/c++/14