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 operation(n):
	if n<=1:
		return 1
	p = 1
	for i in range(1,n+1):
		p *= i
	return p

def calc(n,r):
	return operation(n)//operation(r)//operation(n-r)

stdin = input()
n,m,t = stdin.split()
n = int(n)
m = int(m)
t = int(t)

ans = 0

for i in range(4,n+1):
    if(t-i>=1):
        ans += calc(n,i)*calc(m,t-i)

print(ans)