#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <bit>
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define bw(x) bit_width(unsigned(x))
#define no() { cout << "no\n"; return 0; }

using namespace std;

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, m;
    cin >> n >> m;

    vector<vector<int>> adj(n);
    rep(i, 0, m) {
        int a, b; cin >> a >> b;
        --a, --b;
        adj[a].emplace_back(b);
        adj[b].emplace_back(a);
    }

    int d = bw(n) - 1;
    if (!(n == (1 << d) && ranges::all_of(adj, [d](auto& v) { return v.size() == d; }))) no()

    auto bfs = [&](int s, vector<int>& dist) {
        dist.assign(n, -1);
        dist[s] = 0;
        for (queue<int> q({s}); !q.empty(); q.pop()) {
            int u = q.front();
            for (auto v : adj[u]) {
                if (dist[v] != -1) continue;
                dist[v] = dist[u] + 1;
                q.push(v);
            }
        }
    };
    vector<vector<int>> dist(d+1);
    vector value(n, 0);
    bfs(0, dist[0]);
    rep(i, 0, d) {
        bfs(adj[0][i], dist[i + 1]);
        rep(u, 0, n)
            for (auto v : adj[u])
                // parallel edge to 0<->adj[0][i] (i-th dimension)
                if (dist[0][u] == dist[i + 1][v] && dist[0][u] < dist[0][v])
                    value[v] |= 1 << i;
    }

    rep(u, 0, n)
        for (auto v : adj[u])
            if (popcount(unsigned(value[u] ^ value[v])) != 1) no()

    cout << "yes\n";
}