#include <bits/stdc++.h>
using namespace std;
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
int n, m;
cin >> n >> m;
const int maxn = 1000;
vector<int> adjlist[maxn];
for (int i = 0; i < m; i++) {
int a, b;
cin >> a >> b;
a--, b--;
adjlist[a].push_back(b), adjlist[b].push_back(a);
}
if (m == n - 1)
cout << "YES\n1\n1\n";
else
cout << "NO\n";
return 0;
if (n == 1) {
cout << "YES\n1\n1\n";
} else if (n == 2) {
cout << "YES\n2\n1 1\n";
} else if (n == 3) {
cout << "YES\n2\n2 2\n";
} else {
cout << "NO\n";
}
}
