h,w=map(int,input().split())
p=float(input())
ans = 0
l=[1,0,-1,0]
r=[0,1,0,-1]
for i in range(h):
    for j in range(w):
        t = p
        for k in range(4):
            x = i + l[k]
            y = j + r[k]
            if 0<= x < h and 0<= y <w:
                t*=p
        ans += t

print(ans)