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

current_mod = M % B

if N == 0:
    final_mod = current_mod
else:
    history = [current_mod]
    pos_map = {current_mod: 0}
    steps = 0
    found_cycle = False
    while steps < N:
        steps += 1
        a = (current_mod + D) % B
        e = current_mod
        if a == 0 and e == 0:
            new_mod = 1 % B
        else:
            new_mod = pow(a, e, B)
        if new_mod in pos_map:
            prev_step = pos_map[new_mod]
            cycle_length = steps - prev_step
            remaining = N - steps
            if remaining > 0:
                remaining_steps = remaining % cycle_length
                current_mod = history[prev_step + remaining_steps]
                steps = N  # Advance steps to terminate loop
            else:
                current_mod = new_mod
            break
        else:
            pos_map[new_mod] = steps
            history.append(new_mod)
            current_mod = new_mod
    final_mod = current_mod

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