h,w=map(int,input().split())
p=float(input())
ans = 0

t1 = max(h-2,0) * max(w-2,0) * (p**5)

t2 = 0
if w >= 2:
    t2 += max(h-2,0) * 2 * (p**4)
if h >= 2:
    t2 += max(w-2,0) * 2 * (p**4)

if h >= 2 and w >= 2:
    t3 = 4 * (p**3)
elif h < 2 and w < 2:
    t3 = p
else:
    t3 = 2 * (p**2) 
 
print(t1 + t2 + t3)