#include <iostream>
using namespace std;
int main(){
    int n,m;cin>>n>>m;
    int nw = 0;
    int nwt = 0;
    for(int i = 0; m > i; i++){
        int a,b;cin>>a>>b;
        if(abs(nw-b) > a-nwt){
            cout << "No" << endl;
            return 0;
        }
        nw = b;
        nwt = a;
    }
    cout << "Yes" << endl;
}