Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:21:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<g[x].size();++i){ ^ user.cpp: In function ‘void rdfs(int)’: user.cpp:32:27: 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:48:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb2.in","r",stdin); ^ user.cpp:49:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb2.out","w",stdout); ^ user.cpp:50:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:53:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&x,&y,&z,&p1); ^