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 fact(x):
    if x == 0:
        return 1
    return x * fact(x - 1)

def ncr (n , r):
    if r > n:
        return 0
    return fact(n)//(fact(r)*fact(n-r))

a , b , t = map(int,input().split())
i = 4
ans = 0
while i < t:
    if t - i >= 1:
        ans = ans + ncr(a , i)*ncr(b , t - i)
    i += 1

print(ans)