In file included from /in/Compile/check.cpp:7:
/in/sokoban.hpp:276:24: error: implicit conversion changes signedness: 'int' to 'std::vector::size_type' (aka 'unsigned long') [-Werror,-Wsign-conversion]
        return answers[index];
               ~~~~~~~ ^~~~~
1 error generated.
/in/Compile/Makefile:16: recipe for target 'main' failed
make: *** [main] Error 1