Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:20:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<gr[x].size(); ++i) ^ user.cpp:24:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<gr[y].size(); ++j) ^ user.cpp:30:51: warning: operation on ‘nouy’ may be undefined [-Wsequence-point] noux=noux+nouy-(nouy=noux); ^ user.cpp: In function ‘int main()’: user.cpp:62:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<gr[i].size(); ++j) ^ user.cpp:67:47: warning: operation on ‘nouy’ may be undefined [-Wsequence-point] noux=noux+nouy-(nouy=noux); ^ user.cpp:40:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbpal.in", "r", stdin); ^ user.cpp:41:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbpal.out", "w", stdout); ^ user.cpp:42:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:46:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &x, &y); ^ user.cpp:50:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(v+1); ^ /tmp/cc7sCKtx.o: In function `main': user.cpp:(.text.startup+0xf3): warning: the `gets' function is dangerous and should not be used.