#include <iostream>
using namespace std;

int n, m;
long long t[100001], p[100001];

int main() {
	int i;
	
	cin >> n >> m;
	for (i = 1; i <= m; i++) {
		cin >> t[i] >> p[i];
	}
	
	for (i = 0; i < m; i++) {
		if (t[i + 1] - t[i] < p[i + 1] - p[i]) {
			break;
		}
	}
	
	if (i == m) cout << "Yes" << endl;
	else cout << "No" << endl;
	
	return 0;
}