#include <stdio.h>

int main(int argc, char const *argv[]) {
  int x=0,y=0,n=0,p=0; // X < Y
  double temp=0;
  scanf("%d %d",&x,&y);
  scanf("%d",&n);
  int a[n];
  for (size_t i = 0; i < n; i++) {
    scanf("%d",&a[i]);
  }
  x=x*1000/3600;y=y*1000/3600;
  for (size_t i = 1; i < n; i++) {
    temp=a[i]*x/y;
    if(temp < a[i-1]){
      p=1;
      printf("%lf < %d a[i]=%d X=%d Y=%d n=%d",temp,a[i-1],a[i],x,y,n);
      break;
    }else{
      p=0;
    }
  }
  if(p==1){
    printf("NO\n");
  }else{
    printf("YES\n");
  }
  return 0;
}