#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <charconv>
#include <cstring>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <optional>
#include <random>
#include <set>
#include <unordered_set>
#include <stdexcept>
#include <string>
#include <string_view>
#include <type_traits>
#include <unordered_map>
#include <utility>
#include <variant>
#include <vector>
#include <queue>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(auto i=(a); i<(b); ++i)
#define REP(i,n) rep(i,0,n)
#define all(v) (v).begin(), (v).end()
#define rs resize
#define DBG(x) cerr << __LINE__ << ": " << #x << " = " << (x) << endl

const ld PI = acos(-1.0);
template<class T> using min_queue =
priority_queue<T, vector<T>, greater<T>>;
template<class T> int sz(const T &x) {
    return (int) x.size(); // copy the ampersand(&)!
}

// START OF ACTUAL PROGRAM, START READING HERE

vvi adj;

vi bfs(ll i) {
	vi Q{i};
	vi d(adj.size(),-1);
	d[i] = 0;
	ll j = 0;
	while (j < Q.size()) {
		for (ll k : adj[Q[j]]) {
			if (d[k] >= 0) continue;
			d[k] = d[Q[j]]+1;
			Q.pb(k);
		}
		j++;
	}
	return d;
}

void run() {
	ll n, m;
	cin >> n >> m;
	ll k = 0;
	while ((1<<k) < n) k++;
	if ((1<<k) != n) {
		cout << "no" << endl;
		return;
	}
	adj = vvi(n);
	for (ll i = 0; i < m; i++) {
		ll a, b;
		cin >> a >> b;
		adj[a-1].pb(b-1);
		adj[b-1].pb(a-1);
	}
	if (adj[0].size() != k) {
		cout << "no" << endl;
		return;
	}
	vi W(n, 0);
	vi d0 = bfs(0);
	for (ll i = 0; i < k; i++) {
		vi d = bfs(adj[0][i]);
		for (ll j = 0; j < n; j++) {
			if (d0[j] < 0 || d[j] < 0) {
				cout << "no" << endl;
				return;
			}
			if (d[j] < d0[j]) {
				W[j] += (1<<i);
			}
		}
	}

	unordered_set<ll> S;
	for (ll w : W) {
		S.insert(w);
	}
	if (S.size() != n) {
		cout << "no" << endl;
		return;
	}
	for (ll i = 0; i < n; i++) {
		if (adj[i].size() != k) {
			cout << "no" << endl;
			return;
		}
		for (ll j : adj[i]) {
			if (!has_single_bit((unsigned int) (W[i]^W[j]))) {
				cout << "no" << endl;
				return;
			}
		}
	}
	cout << "yes" << endl;
}

signed main() {
    // DON'T MIX "scanf" and "cin"!
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout << fixed << setprecision(20);
    run();
    return 0;
}