Compilare: user.cpp: In function ‘void bfs()’: user.cpp:28:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < g[u1].size(); ++ k) { ^ user.cpp: In function ‘int dfs(int)’: user.cpp:42:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < g[u1].size(); ++ k) { ^ user.cpp: In function ‘int main()’: user.cpp:81:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("senat.in", "r", stdin); ^ user.cpp:82:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("senat.out", "w", stdout); ^ user.cpp:85:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &n, &m); ^ user.cpp:90:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccT43SeO.o: In function `main': user.cpp:(.text.startup+0xa0): warning: the `gets' function is dangerous and should not be used.