In file included from /in/Compile/check.cpp:7:
/in/sokoban.hpp:71:39: error: implicit conversion changes signedness: 'int' to 'size_t' (aka 'unsigned long') [-Werror,-Wsign-conversion]
    while (left < cols && is_wall_col(left)) ++left;
                          ~~~~~~~~~~~ ^~~~
/in/sokoban.hpp:78:42: error: implicit conversion changes signedness: 'int' to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::size_type' (aka 'unsigned long') [-Werror,-Wsign-conversion]
        newGrid.push_back(grid[i].substr(left, right - left + 1));
                                  ~~~~~~ ^~~~
/in/sokoban.hpp:78:56: error: implicit conversion changes signedness: 'int' to 'unsigned long' [-Werror,-Wsign-conversion]
        newGrid.push_back(grid[i].substr(left, right - left + 1));
                                                     ~ ^~~~
/in/sokoban.hpp:71:17: error: comparison of integers of different signs: 'int' and 'size_t' (aka 'unsigned long') [-Werror,-Wsign-compare]
    while (left < cols && is_wall_col(left)) ++left;
           ~~~~ ^ ~~~~
4 errors generated.
/in/Compile/Makefile:16: recipe for target 'main' failed
make: *** [main] Error 1