Compilare: user.cpp: In function ‘bool dfs(int)’: user.cpp:43:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<g[node].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:94:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<g[i].size();++j) ^ user.cpp:60:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pari.in","r",stdin); ^ user.cpp:61:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pari.out","w",stdout); ^ user.cpp:63:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&d); ^ user.cpp:67:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ",&x); ^ user.cpp:69:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ /tmp/ccOfyIgw.o: In function `main': user.cpp:(.text.startup+0xc3): warning: the `gets' function is dangerous and should not be used.