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

int main(){
    int n,m;
    cin >> n >> m;
    int ct=0,cp=0;
    for(int i=0; i<m; i++){
        int t,p;
        cin >> t >> p;
        if(t-ct < p-cp){
            cout << "No" << endl;
            return 0;
        }
        ct = t;
        cp = p;
    }
    cout << "Yes" << endl;
}