//  Flight Routes Check

#include<bits/stdc++.h>

using namespace std;

void dfs(bitset<(int)1e5>& v, int s, vector<vector<int>> &g) {
    v[s] = true;
    for (auto &e: g[s]) {
        if (!v[e]) {
            dfs(v, e, g);
        }
    }
}

int main() {
    int n, m; cin >> n >> m;
    vector<vector<int>> g(n);
    vector<vector<int>> r(n);
    for (int i{}; i < m; i++) {
        int a, b; cin >> a >> b; a--; b--;
        g[a].push_back(b);
        r[b].push_back(a);
    }
    bitset<(int)1e5> v = 0;
    dfs(v, 0, g);
    bitset<(int)1e5> v2 = 0;
    if (v.count() != n) {
        cout << "NO" << endl;
        for (int i{}; i < n; i++) {
            if (!v[i]) {
                cout << 1 << " " << i + 1 << endl;
                return 0;
            }
        }
    } else {
        dfs(v2, 0, r);
        if (v2.count() != n) {
            cout << "NO" << endl;
            for (int i{}; i < n; i++) {
                if (!v2[i]) {
                    cout << i + 1 << " " << 1 << endl;
                    return 0;
                }
            }
        } else {
            cout << "YES" << endl;
        }
    }
    return 0;
}