Compilare: main.cpp: In function 'int bfs(int, int)': main.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<g[q.front()].size(); i++){ ~^~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:34:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("grea.in", "r",stdin); ^ main.cpp:35:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("grea.out", "w",stdout); ^ main.cpp:37:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ main.cpp:40:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%1d", &v[j][i]); ^