#include <iostream>
#include <string>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int main(){
	int N, M; cin >> N >> M;
	LL T = 0, P = 0;
	bool ok = true;
	rep(i, M){
		LL t, p; cin >> t >> p;
		if (abs(p - P) > t - T) ok = false;
		T = t; P = p;
	}

	cout << (ok ? "Yes" : "No") << endl;

	return 0;
}