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

D_mod = D % B
current = M % B

if N == 0:
    res = current
else:
    history = [current]
    seen = {current: 0}
    found_cycle = False
    ans = current

    for step in range(1, N + 1):
        a = (current + D_mod) % B
        e = current
        if a == 0 and e == 0:
            next_x = 1 % B
        else:
            next_x = pow(a, e, B)
        
        if next_x in seen:
            cycle_start = seen[next_x]
            cycle_length = step - cycle_start
            remaining = N - step
            pos = cycle_start + (remaining % cycle_length)
            ans = history[pos]
            found_cycle = True
            break
        
        seen[next_x] = step
        history.append(next_x)
        current = next_x
        
        if step == N:
            ans = current
            found_cycle = True
            break
    
    if not found_cycle:
        ans = current

if ans < 10:
    print(ans)
else:
    print('A')