ЗОШ конденсация debug

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
using namespace std;
using ll = long long;
using ld = long double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}
int n,m;
vector <vector<int>>G;
vector <vector<int>> reG;
const int wh = 0, gr = 1, bl = 2;
vector <int> clr;
vector <int> tp;


bool paint = 0;
int cmp_num = 0;

vector <int> comp;

void dfs(int v, int pr){
    clr[v] = gr;
    if (paint) comp[v] = cmp_num;
    for (int u: G[v]){
        if (u == pr) continue;
        else if (clr[u] == wh){
            dfs(u, v);
        }
        else if (clr[u] == gr){
            cout<<-1<<"\n";
            exit(0);
        }
    }
    clr[v] = bl;
    tp.push_back(v+1);
}




int main()
{
    ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	G.resize(n);
	clr.assign(n, wh);
	comp.resize(n);
	for (int i=0;i<m;++i){
        int a,b; cin>>a>>b;
        a--; b--;
        G[a].push_back(b);
        reG[b].push_back(a);
	}
	for (int i = 0;i<n;++i){
        if (clr[i] == wh){
            dfs(i, -1);
        }
	}
	reverse(tp.begin(), tp.end());
	cv(tp);
	paint = 1;
	for (int i=0;i<n;++i){
        if (clr[i] == wh){
            dfs(i, -1);
            cmp_num++;
        }
	}

}