#include <bits/stdc++.h>
using namespace std;
using ll = long long;

array<unordered_set<ll>, 55> adj;


int main() {

    ll n, m;
    cin >> n >> m;
    ll a, b;
    for (int i = 0; i < m; i++) {
        cin >> a >> b;
        adj[a].insert(b);
    }
    vector<vector<ll>> u;
    for (int i = 1; i <= n; i++) {
        auto a = adj[i];
        for (auto s: a) {
            if (adj[s].count(i)) {
                cout << "NO" << endl;
                return 0; 
            }
            u.push_back({});
            u.back().push_back(i);
            u.back().push_back(s);
            for (int j = 1; j <= n; j++) {
                if (j != i && j != s) u.back().push_back(j);
            }
            u.push_back({});
            for (int j = n; j > 0; j--) {
                if (j != i && j != s) u.back().push_back(j);
            }
            u.back().push_back(i);
            u.back().push_back(s);
        }
    }

    cout << "YES" << endl << u.size() << endl;

    for (auto x: u) {
        for (auto y: x) cout << y << " ";
        cout << endl;
    }



    return 0;
}