#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;


int main(){
    long long n, m, prep = 0, pret = 0, dt = 0, t, p;
    cin >> n >> m;
    for (int i = 0; i < m; i++){
        cin >> t >> p;
        dt = t - pret;
        if (dt < abs(prep - p)){
            cout << "No" << endl;
            exit(0);
        }
        pret = t;
        prep = p;
    }
    cout << "Yes" << endl;
}