#include<iostream> #include<string> #include<vector> #include<algorithm> #include<bitset> #include<set> #include<map> #include<stack> #include<queue> #include<deque> #include<list> #include<iomanip> #include<cmath> #include<cstring> #include<functional> #include<cstdio> #include<cstdlib> #include<numeric> using namespace std; #define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++) #define rep(i, n) repr(i, 0, n) #define INF 2e9 #define MOD 1000000007 //#define MOD 998244353 #define LINF (long long)4e18 #define jck 3.141592 const double EPS = 1e-10; using ll = long long; using Pi = pair<int,int>; using Pl = pair<ll,ll>; int main(){ int n,m; cin >> n >> m; int now = 0; ll time = 0; rep(i,m){ ll t; cin >> t; int p; cin >> p; if(t-time < abs(p-now)){ cout << "No" << endl; return 0; } time = t; now = p; } cout << "Yes" << endl; }