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 pascal_triangle(n):
    pt = [[1] + [0] * n for _ in range(n + 1)]

    for i in range(1, n + 1):
        for j in range(1, i + 1):
            pt[i][j] = pt[i - 1][j] + pt[i - 1][j - 1]
    return pt


n, m, t = map(int, input().split())
c = pascal_triangle(n + m)
summ = 0

for boys in range(max(4, t - m), min(n, t - 1) + 1):
    # (Число сочетаний по boys мальчиков из n) * (число сочетаний по (t - boys) девочек из m)
    summ += c[n][boys] * c[m][t - boys]

print(summ)

