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

if N == 0:
    res = M % B
else:
    current_mod = M % B
    history = [current_mod]
    pos_map = {current_mod: 0}
    found_cycle = False
    cycle_start = 0
    cycle_length = 0

    for step in range(1, N + 1):
        a = (current_mod + D) % B
        e = current_mod

        if a == 0 and e == 0:
            next_mod = 1 % B
        elif a == 0:
            next_mod = 0 % B
        else:
            next_mod = pow(a, e, B)

        if next_mod in pos_map:
            cycle_start = pos_map[next_mod]
            cycle_length = len(history) - cycle_start
            remaining = N - step
            final_pos = cycle_start + (remaining % cycle_length)
            current_mod = history[final_pos]
            found_cycle = True
            break
        else:
            pos_map[next_mod] = len(history)
            history.append(next_mod)
            current_mod = next_mod

    res = current_mod

# Convert res to B base last digit
if res < 10:
    print(res)
else:
    print('A')