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
#coding:utf-8

#組み合わせnCrの値を返す
#何度も計算する場合は遅いので、メモ化などの処置を。要検討
def combination(n,r):
	perm_r, perm_n = 1,1
	if n/2 < r : 
		return combination(n,n-r)
	for i in xrange(1,r+1):
		perm_r *= i
		perm_n *= (n+1-i)
	return(perm_n/perm_r)


#順列nPrを返す
def permutation(n,r):
	perm = 1
	for i in range(n-r+1,n+1)[::-1]:
		perm *= i
	return(perm)

n,m,t = raw_input("").split()
n = int(n); m = int(m); t = int(t)
ans = 0
for i in xrange(1,m+1):
	if n<t-i : continue
	if t-i<4 : break
	ans += combination(n,t-i) * combination(m, i)
print ans
