func main()
	var n: int :: cui@inputInt()
	var a: []int :: #[n - 1]int
	for i(0, n - 2)
		do a[i] :: cui@inputInt()
	end for
	
	var num: int :: 0
	var ans: int :: 0
	for i(0, n - 2)
		var b: int :: cui@inputInt()
		var c: int :: cui@inputInt()
		do num :+ c - b
		do ans :+ num * a[i]
	end for
	do cui@print("\{ans}\n")
end func