/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.08.31 18:23:03
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n,m;cin >> n >> m;
    int now_pos = 0;
    int now_time = 0;
    for (int i = 0; i < m; i++) {
        int t,p;cin >> t >> p;
        if (abs(now_pos-p) <= t-now_time) {
            now_time = t;
            now_pos = p;
        }
        else {
            puts("No");
            return 0;
        }
    }
    puts("Yes");
    return 0;
}