n,m = map(int,input().split())
p = float(input())
ans = 0.0
r = [p**i for i in range(9)]
if n==m==1:
    print(r[1])
elif n==1 or m==1:
    print(r[2]*2+r[3]*(n*m-2))
else:
    print(r[3]*4+r[4]*(n+m-4)*2+r[5]*(n-2)*(m-2))