Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:14:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<vec[x].size(); i++) ~^~~~~~~~~~~~~~ user.cpp: In function ‘void dfs2(int)’: user.cpp:28:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<vec2[x].size(); i++) ~^~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:63:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<ans[i].size(); j++) ~^~~~~~~~~~~~~~ user.cpp:37:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in","r",stdin); ^ user.cpp:38:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out","w",stdout); ^ user.cpp:40:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:43:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x1,&x2); ^