Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:35:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<a[el].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:73:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apdm.in", "rt", stdin); ^ user.cpp:74:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apdm.out", "wt", stdout); ^ user.cpp:76:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:80:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^