#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;
    
    vector<vector<int>> to(n); 
    rep(i, m) {
        int a, b;
        cin >> a >> b;
        --a; --b;
        to[a].push_back(b);
        to[b].push_back(a);
    }
    
    rep(i, n) {
        if (to[i].size() > 2) {
            puts("No");
            return 0;
        }
    }
    
    puts("Yes");
    
    return 0;
}