Compilare: user.cpp: In function ‘int main()’: user.cpp:66:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < bfs_tree.size(); k++) ^ user.cpp:40:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reinvent.in", "r", stdin); ^ user.cpp:41:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reinvent.out", "w", stdout); ^ user.cpp:43:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &x); ^ user.cpp:48:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &u, &v); ^ user.cpp:54:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &u); ^