#include <iostream>
#include <vector>
using namespace std;
///vector is an array with size of k, don't be afraid
int main() {
	int n, k;
	cin >> n >> k;
	vector<int> a1 (k);  //nums of left bus st
	vector<int> a2 (k);  //nums of right bus st
	for (int i = 0; i < k; i++)
		cin >> a1[i] >> a2[i];
	int left = a1[0], right = a2[0];
	for (int w = 0; w < 2; w++) // double cycle
        for (int i = 1; i < k; i++)
			if ((a1[i] >= left && a1[i] <= right)||(a2[i] >= left && a2[i] <= right))
            {
                right = max(right, a2[i]);
                left = min(left, a1[i]);
            }
	if (left == 1 && right == n) cout << "YES";
	else cout << "NO";
	return 0;
}