Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:20:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<ve[x].size();i++) ^ user.cpp: In function ‘void calc(int)’: user.cpp:39:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<ve[x].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:49:37: 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:50:39: 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:53:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:56:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&x,&y,&z); ^ user.cpp:63:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&k); ^ user.cpp:66:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^