#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;
int main(){
    int n,m;
    cin >> n >> m;
    ll now = 0;
    ll tm = 0;
    while(m--){
        ll t,p;
        cin >> t >> p;
        if(abs(t-tm) < abs(now-p)){
            cout << "No\n";
            return 0;
        }
        now = p;
        tm = t;
    }
    cout << "Yes\n";
    return 0;
}