#include "bits/stdc++.h"
using namespace std;

#define int long long

#define ll long long
#define rep(i,n) for(ll i = 0; i < (n); i++)
#define P pair<ll,ll>
#define ld long double
ll INF = (1LL << 60);
int mod = 1000000007;

int N, M;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> N >> M;
	int now = 0;
	int before = 0;
	rep(i, M) {
		int t, p; cin >> t >> p;
		int need = abs(p - now);
		if (need > t - before) {
			cout << "No" << endl; return 0;
		}
		before = t;
		now = p;
	}
	cout << "Yes" << endl;
	return 0;
}