Compilare: user.cpp:2:176: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] int i,j,n,m,o[50010];std::vector<int>v[50010];std::ifstream f("sortaret.in");std::ofstream t("sortaret.out");void d(int p){o[p]=1;for(int j:v[p])if(!o[j])d(j);t<<p<<" ";}main(){int x,y;f>>n>>m;for(i=1;i<=m;++i)f>>x>>y,v[y].push_back(x);for(i=1;i<=n;++i)if(!o[i])d(i);} ^