import decimal

h, w = map(int, input().split())
p = decimal.Decimal(input())

if h == 1 and w == 1:
    ans = p
elif h == 1:
    ans = p ** 2 * 2 + (w - 2) * p ** 3
elif w == 1:
    ans = p ** 2 * 2 + (h - 2) * p ** 3
else:
    ans = 0
    ans += p ** 3 * 4
    ans += p ** 4 * (2 * w + 2 * h - 8)
    ans += p ** 5 * (h - 2) * (w - 2)

print(ans)