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 C(n, k):
    result = 1
    for i in range(1, k + 1):
        result = result * (n - i + 1) / i
    return result

n, m, t = raw_input().split()
n, m, t = int(n), int(m), int(t)

c = 0
for a in range(4, n + 1):
    b = t - a
    if b < 1:
        continue

    c += C(n, a) * C(m, b)

print c
