Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:21:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<gr[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:31:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amici2.in", "r", stdin); ^ user.cpp:32:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amici2.out", "w", stdout); ^ user.cpp:33:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:36:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:40:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^