Compilare: user.cpp: In function ‘void DFS(int, int)’: user.cpp:7:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define FOR(i,s,d) for(i=(s);i<(d);++i) ^ user.cpp:29:5: note: in expansion of macro ‘FOR’ FOR(j,0,v[x].size()) DFS(v[x][j],niv+1); ^ user.cpp: In function ‘int main()’: user.cpp:49:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb.in","r",stdin); ^ user.cpp:50:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb.out","w",stdout); ^ user.cpp:51:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:52:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] FOR(i,1,n+1) scanf("%d",&a[i]); ^ user.cpp:53:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] FOR(i,1,n) scanf("%d",&x),v[x].pb(i+1); ^ user.cpp:55:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:58:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^