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 f(n):
	fact = 1
	for i in range(n):
		fact = fact * (i+1)
	return fact

def c(n, k):
	return f(n)/((f(n-k)*f(k)))

n, m, t = map(int, raw_input().split(' '))
ans = 0
for a in range(4,n+1):
	b = t-a
	if(b <= 0): break
	if(b <= m): ans = ans + c(n,a)*c(m,b)
print ans