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(k):
    res = 1
    for i in range(1, k+1):
        res *= i
    return res
def Cnk(n, k):
    return fact(n) // (fact(k) * fact(n-k))

n, m, t = map(int, input().split(' '))

minN = 4
minM = 1

total = 0

N = minN
while N + minM <= t:
    M = t - N

    if N <= n and M <= m:
        total += Cnk(n, N) * Cnk(m, M)

    N += 1

print(total)