N, M = map(int, input().split())
P = float(input())
if N == 1 and M == 1:
    print(P)
elif N == 1:
    print((P ** 2) * 2 + (P ** 3)*(M - 2))
elif M == 1:
    print((P ** 2) * 2 + (P ** 3) * (N - 2))
else:
    print((P ** 3) * 4 + (P ** 4) * (N - 2) * 2 + (P ** 4) * (M - 2) * 2 + (P ** 5) * (N - 2) * (M - 2))