Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:18:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[x].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:75:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<sol[i].size();j++) ^ user.cpp:52:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin); ^ user.cpp:53:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out","w",stdout); ^ user.cpp:54:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:57:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^