#include using namespace std; typedef long long ll; #define REP(i,n) for(int i=0,_n=(int)(n);i<_n;++i) #define ALL(v) (v).begin(),(v).end() #define CLR(t,v) memset(t,(v),sizeof(t)) templateostream& operator<<(ostream& os,const pair&a){return os<<"("<void chmin(T&a,const T&b){if(a>b)a=b;} templatevoid chmax(T&a,const T&b){if(avoid pv(T a,T b){for(T i=a;i!=b;++i)cerr<<(*i)<<" ";cerr<void pv(T a,T b){} #endif ll nextLong() { ll x; scanf("%lld", &x); return x;} int main2() { int N = nextLong(); int M = nextLong(); ll Tp = 0; ll Pp = 0; bool ok = true; REP(i, M) { ll T = nextLong(); ll P = nextLong(); if ((T - Tp) >= abs(P - Pp)) { } else { ok = false; } Tp = T; Pp = P; } cout << (ok ? "Yes":"No") << endl; return 0; } int main() { #ifdef LOCAL for (;!cin.eof();cin>>ws) #endif main2(); return 0; }