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 comb(x, y):
	if x < y : return 0
	if x == y : return 1
	y = max(y, x - y)
	r1 = range(y + 1, x + 1)
	r2 = range(1, x - y + 1)
	f = lambda x, y : x * y
	return reduce(f, r1) / reduce (f, r2)

if __name__ == "__main__":
	n, m, t = [int(x) for x in raw_input().split(" ")]
	ans = 0
	for i in range(t - 4):
		ans += comb(n, i + 4) * comb(m, t - 4 - i)
	print ans
