def main():
    line = input(
    "Enter 4 numbers, g, p, a, b (g and p are two primes, a - Bob's code, b - Alice's ")
    # i.e. 7,1000000007,30,15 -> yields: 983383752 as mutual key
    inp = line.split(',')
    g = int(inp[0])
    p = int(inp[1])
    a = int(inp[2])
    b = int(inp[3])
    bob = pow(g,a,p)
    alice = pow(g,b,p)
    mutual_code = pow(alice,a,p)
    mutual2 = pow(bob,b,p)

    if mutual2 == mutual_code:
        print(mutual_code)

if __name__ == '__main__':
    main()