N, M = map(int, input().split())
p = float(input())

if N == M == 1:
    print(p)
elif N == 1:
    print(p**3 * (M-2) + p**2 * 2)
elif M == 1:
    print(p**3 * (N-2) + p**2 * 2)
else:
    print(p**5 * (N-2) * (M-2) + p**4 * ((N-2)*2 + (M-2)*2) + p**3 * 4)