#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int p[1005];
int get (int x) {
if (x == p[x]) return x;
return p[x] = get(p[x]);
}
void u (int x, int y) {
x = get(x), y = get(y);
if (x == y) return;
p[x] = y;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, m; cin >> n >> m;
vector <int> cnt(n + 1, 0);
int cntr = 0;
bool ok = 1;
for (int i = 1; i <= n; i++) p[i] = i;
for (int i = 1; i <= m; i++) {
int x, y; cin >> x >> y;
if (get(x) == get(y)) ok = 0;
u(x, y);
cnt[x]++;
cnt[y]++;
cntr = max(cnt[x], cntr), cntr = max(cntr, cnt[y]);
}
if (m == n - 1 && ok && (cntr < 3)) cout << "YES\n" << "1\n1";
else cout << "NO\n";
return 0;
}
