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
'''input
4 3 5
'''
from sys import stdin, setrecursionlimit
import math
from bisect import bisect_left


def comb(a, b):
	if b > a :
		return 0

	return math.factorial(a) //(math.factorial(a - b) * math.factorial(b))

# main starts
n, m, t = list(map(int, stdin.readline().split()))
if n < 4 or t < 1:
	print(0)
	exit()

first = 4
second = t - first
ans = 0
while first <= n and second >= 1:
	ans += comb(n, first) * comb(m, second)
	first += 1
	second = t - first
print(ans)