func main()
	var p: int :: cui@inputInt() % 10
	var q: int :: cui@inputInt() % 10
	var r: int :: cui@inputInt() % 10
	var k: int :: cui@inputInt()
	var a: []int :: #[1005]int
	do a[1] :: p
	do a[2] :: q
	do a[3] :: r
	for i(4, 1004)
		do a[i] :: (a[i - 1] + a[i - 2] + a[i - 3]) % 10
	end for
	var len: int
	for i(5, 1004)
		if(a[i] = a[4] & a[i - 1] = a[3] & a[i - 2] = a[2])
			do len :: i - 4
			break i
		end if
	end for
	do k :- 4
	do k :% len
	
	var ans: int :: a[k + 4]
	do cui@print("\{ans}\n")
end func