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(x):
    if (x == 0):
        return 1
    return fact(x - 1) * x

def c(n, k):
    if (k < 0):
        return 0
    if (k > n):
        return 0
    return fact(n) / fact(k) / fact(n - k)

n, m, t = raw_input().split()
ans = 0
n = int(n)
m = int(m)
t = int(t)
for i in range(4, n + 1):
    if (t - i > 0):
        ans += c(n, i) * c(m, t - i)

print ans
