#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main(){
    int N,M;
    cin>>N>>M;
    int n=0,t=0;
    while(M--){
        int a,b;
        cin>>a>>b;
        if(abs(a-t)<abs(b-n)){
            puts("No");
            return 0;
        }
        n=b,t=a;
    }
    puts("Yes");
}