There are n boys and m girls attending a theatre club. To set a play "The Big Bang Theory", they need to choose a group containing exactly t actors containing no less than 4 boys and no less than one girl. How many ways are there to choose a group? Of course, the variants that only differ in the composition of the troupe are considered different.

Perform all calculations in the 64-bit type: long long for С/С++, int64 for Delphi and long for Java.

Input

The only line of the input data contains three integers n, m, t (4 ≤ n ≤ 30, 1 ≤ m ≤ 30, 5 ≤ t ≤ n + m).

Output

Find the required number of ways.

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specificator.

Examples

Input

5 2 5


Output

10


Input

4 3 5


Output

3

def C(n, k):
	def fact(x):
		r = 1
		for i in range(1, x + 1):
			r *= i
		return r
	up = 1
	lower = fact(n - k)
	for i in range(n, k, -1):
		up *= i
	res = up // lower
	return res
if __name__ == "__main__":
	n, m, t = (int(x) for x in input().split())
	nb, ng = 0, 0
	ans = 0
	for b in range(4, n + 1):
		g = t - b

		if g < 1 or g > m:
			continue
		nb, ng = C(n, b), C(m, g)
		ans += nb*ng
	print(ans)
		