#include<bits/stdc++.h>

using namespace std;
using ll = long long;


int main()
{
	int n, m; cin >> n >> m;
	vector<int> t(m+1), p(m+1);
	for(int i = 1; i <= m; i++)cin >> t[i] >> p[i];
	bool ok = true;
	for(int i = 0; i < m; i++) {
		if(t[i+1] - t[i] < abs(p[i+1]-p[i]))ok = false;
	}
	cout << (ok ? "Yes" : "No") << endl;
}