Compilare: user.cpp: In function ‘void dfsx(int, long long int)’: user.cpp:52:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<vn.size();++i) { ^ user.cpp: In function ‘int main()’: user.cpp:66:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("riremito.in","r",stdin); ^ user.cpp:67:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("riremito.out","w",stdout); ^ user.cpp:68:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:72:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%lld",&x,&y,&z); ^ user.cpp:76:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&K); ^ user.cpp:80:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&start); ^