/in/foo.cc: In function 'bool dfs(std::vector<std::vector<char> >&, int, int)':
/in/foo.cc:6:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    6 |     if (x == grid.size() - 1) return true;
      |         ~~^~~~~~~~~~~~~~~~~~
/in/foo.cc:10:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |         if (ny >= 0 && ny < grid[0].size() && grid[nx][ny] == '!') {
      |                        ~~~^~~~~~~~~~~~~~~~