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

#define forn(i, n) for(int i = 1; i <= n; ++i)
#define MAX 100002

using namespace std;

vector<set<int>>graph(MAX);
vector<int>oto;
vector<int> ans;

int mark[MAX];
int n, m;

bool dfs(int v) {
    if (mark[v] != 0) return 0;
    mark[v] = 1;
    for( int x : graph[v]) {
        dfs(x);
        if (mark[x] == 1)
            return 1;
    }
    oto.push_back(v);
    mark[v] = 2;
    return false;
}

void top_sort() {
    forn(i, n)
        mark[i] = 0;
    oto.clear();
    forn(i, n)
        if(!mark[i]) {
            if (dfs(i) == 1) {
                cout << "NO" << "\n";
                return;
            }
        }
    reverse(oto.begin(), oto.end());
    for(int i: oto) {
        if (*graph[i].find(i + 1)) {
            ans.push_back(i);
            for (int i: ans)
                cout << i << " ";
            return;
        } else
        {
            cout << "NO" << "\n";
            return;
        }

    }
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    cin >> n >> m;

    int u, v;
    forn(i, m) {
        cin >> v >> u;
        graph[v].insert(u);
    }
    top_sort();
}