Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:27:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ^ user.cpp: In function ‘void dfs2(int)’: user.cpp:43:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<g[x].size();i++) ^ user.cpp: In function ‘void sort_top2()’: user.cpp:61:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<ctc[i].size();j++) ^ user.cpp: In function ‘void read()’: user.cpp:16:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:19:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] {scanf("%d %d",&x,&y); ^ user.cpp: In function ‘int main()’: user.cpp:67:32: 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:68:34: 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); ^