#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

const int MN = 100001;

int is[MN];
int n;
vector <vector<int>> vert(MN);
int beg = -1;


bool dfs (int v, vector <int>& ans) {
    is[v] = 1;
    for (int i = 0; i < vert[v].size(); i++) {
        if (is[vert[v][i]] == 0) {
            if (dfs(vert[v][i], ans))
                return true;
        }
        else if (is[vert[v][i]] == 1) {
            beg = vert[v][i];
            return true;
        }
    }
    is[v] = 2;
    ans.push_back(v);
    return false;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int m, x, y;
    cin >> n >> m;
    vector <int> ans;
    for (int j = 0 ; j < m; j++) {
        cin >> x >> y;
        vert[x].push_back(y);
    }
    for (int i = 0; i < n; i++){
        is[i] = 0;
    }
    for (int i = 0; i < n; i++) {
        if (dfs(i, ans))
            break;
    }
    reverse(ans.begin(), ans.end());
    if (beg != -1) {
        cout << -1;
        return 0;
    }
    for (int i = 0; i < n; i++) {
        cout << ans[i] << ' ';
    }
    return 0;
}