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 f(n):
    r = 1
    for i in range(1, n + 1):
        r *= i
    return r

def un(n,m):
    if (m > n):
        return 0
    return f(n) / (f(m) * f(n - m))

R = lambda : map(int, raw_input().split(' '))
n, m, t = R()
res = 0
for i in range(4, n + 1):
    sm = un(n, i);
    for j in range(1, m + 1):
        if ((j +i) == t):
            tmp = un(m, j)
            res += tmp * sm
print res  