koba, master = gets.chomp.split(" ").map(&:to_f)
koba /= 3.6
master /= 3.6
flag = true
inter = gets.chomp.to_f
list = gets.chomp.split(" ").map(&:to_f)
list.unshift(0.0)
list.each_with_index do |val, ind|
	if list.length > ind + 1
		flag = false if list[ind + 1] < master * (val / koba)
	end
end
puts flag == false ? "NO" : "YES"