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 fac(n):
  return (1 if n <= 1 else n * fac(n - 1))

def cnk(n, k):
  if k > n or k < 0:
    return 0
  return (fac(n) // fac(k)) // fac(n - k)

n, m, t = map(int, input().split())
ans = 0
tt = t - 1
while tt >= 4:
  ans += cnk(n, tt) * cnk(m, t - tt)
  tt -= 1
print(ans)