#include<bits/stdc++.h>
using namespace std;

int main(){
    int n,m;cin >> n >> m;
    int now = 0;
    int bt = 0;
    for(int i=0;i<m;i++){
        int t,p;cin >> t >> p;
        int l = abs(now - p);
        int time = t - bt;
        if(l <= time){
            now = p;
            bt = t;
        }
        else{
            cout << "No" << endl;
            return 0;
        }
    }
    cout << "Yes" << endl;
    return 0;
}