#!/Users/takaesumizuki/anaconda3/envs/hoge/bin/python

def main():
	A, B = map(int, input().split())
	P = float(input())
	if A < B : A, B = B, A
	if A == 1 and B == 1:
		print(P)
		return 
	if A == 1:
		ans = (A - 2) * (p ** 3) + 2 * (p ** 2)
		print(ans)
		return
	ans = 4 * (P ** 3) + (A + B - 4) * 2 * (P ** 4) + (A - 2) * (B - 2) * (P ** 5)
	print(ans)
	return

if __name__ == '__main__':
	main()