#include #define rep(i,n) for(int i = 0; i < (n); i++) using namespace std; typedef long long ll; int main(){ cin.tie(0); ios::sync_with_stdio(0); int N,M; cin >> N >> M; vector> TP; TP.push_back({0, 0}); rep(i,M) { ll t,p; cin >> t >> p; TP.push_back({t, p}); } int ok = 1; rep(i,M) { ll dt = TP[i + 1].first - TP[i].first; ll dp = TP[i + 1].second - TP[i].second; ok &= dp <= dt; } cout << (ok ? "Yes" : "No") << endl; }