#include <iostream>
using namespace std;
int main() {
    int n, m; cin >> n >> m;
    int now = 0, place = 0;
    bool c = 1;
    for(int i = 0; i < m; ++i) {
        int t, p; cin >> t >> p;
        if(max(t - now, now - t) < max(p - place, place - p)) {
            c = 0;
            break;
        }
        now = t;
        place = p;
    }
    if (c) {
        cout << "Yes" << endl;
    }
    else {
        cout << "No" << endl;
    }
}