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

int main() {
	int64_t n, m; cin >> n >> m;
	int64_t pp = 0, pt = 0;
	while(m--) {
		int64_t t, p; cin >> t >> p;
		if(abs(pt - t) < abs(pp - p)) {
			cout << "No" << '\n';
			return 0;
		}
		pt = t, pp = p;
	}
	cout << "Yes" << '\n';
	return 0;
}