import random
from math import gcd

def pfact(m):
	pf = {}
	for i in range(2,int(m**0.5)+1):
		while m%i == 0:
			pf[i] = pf.get(i,0) + 1
			m //= i
	if m>1 : pf[m]=1
	return pf


def euler(m):
	#pfactのdefが必須
	tmp = pfact(m)
	ans = 1
	for i, j in tmp.items():
		ans = ans * (i**(j-1)) * (i-1)
	return ans


while True:
	m = int(input())
	d = int(input())
	n = int(input())
	b = int(input())
	def fast(m,d,n,b):
		nb = 277200
		v = [[0] * nb for i in range(61)]
		for i in range(nb):
			if (i+d)%nb != 0:
				v[0][i] = pow(i+d, i, nb)
			else:
				v[0][i] = 0

		for i in range(60):
			for j in range(nb):
				v[i+1][j] = v[i][v[i][j]]

		if n == 0:
			r = '0123456789ABCDEFG'
			return r[m % b]

		if m == 0 and d == 0:
			n -= 1
			m = 1

		m %= nb
		for i in range(61):
			if (n >> i) & 1:
				m = v[i][m]

		r = '0123456789ABCDEFG'
		return r[m % b]

	print(fast(m,d,n,b))
	break