func main()
	var x: int :: cui@inputInt()
	var y: int :: cui@inputInt()
	var n: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	
	var sumX: int :: 0
	var sumY: int :: a[0]
	for i(0, n - 2)
		do sumX :+ a[i]
		do sumY :+ a[i + 1]
		if(sumX * y > sumY * x)
			do cui@print("NO\n")
			ret
		end if
	end for
	
	do cui@print("YES\n")
end func