#include <iostream>
#include <vector>
using namespace std;

int main(){
    int n,m;
    cin >> n >> m;
    int now = 0;
    while(m--){
        int t,p;
        cin >> t >> p;
        if(abs(t-now) < abs(t-p)){
            cout << "No\n";
            return 0;
        }
        now = p;
    }
    cout << "Yes\n";
    return 0;
}