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:
    if h == 1:
        t2 += (w - 2) * (p ** 3)
    else:
        t2 += (w - 2) * 2 * (p**4)
        
if h >= 2:
    if w == 1:
        t2 += (h - 2) * (p ** 3)
    else:
        t2 += (h - 2) * 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)