Compilare: main.cpp: In function 'int main()': main.cpp:76:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1;i < possible.size();i++){ ~~^~~~~~~~~~~~~~~~~ main.cpp:32:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("snake.in", "r", stdin); ^ main.cpp:33:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("snake.out", "w", stdout); ^ main.cpp:35:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &n, &m, &l); ^ main.cpp:38:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i][j]); ^