def find_cycle(m0, D_mod, B):
    seen = {}
    path = []
    current = m0
    step = 0
    while current not in seen:
        seen[current] = step
        path.append(current)
        base = (current + D_mod) % B
        exponent = current
        if base == 0 and exponent == 0:
            next_m = 1 % B
        else:
            next_m = pow(base, exponent, B)
        current = next_m
        step += 1
    cycle_start = seen[current]
    cycle_length = step - cycle_start

    # Generate the loop elements
    loop = []
    if cycle_length > 0:
        loop.append(current)
        for _ in range(cycle_length - 1):
            base = (loop[-1] + D_mod) % B
            exponent = loop[-1]
            if base == 0 and exponent == 0:
                next_m = 1 % B
            else:
                next_m = pow(base, exponent, B)
            loop.append(next_m)
    return path, cycle_start, cycle_length, loop

# Read input
M = int(input())
D = int(input())
N = int(input())
B = int(input())

D_mod = D % B
initial_m = M % B

path, cycle_start, cycle_length, loop = find_cycle(initial_m, D_mod, B)

if N < len(path):
    final_m = path[N]
else:
    remaining = N - cycle_start
    index = remaining % cycle_length
    final_m = loop[index]

# Convert to B-based last digit
if final_m < 10:
    print(final_m)
else:
    print('A')