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(n):
    if n <= 1:
        return 1
    ans = 1
    for i in range(2, n + 1):
        ans *= i
    return ans

def calcC(n, k):
    return fact(n) / fact(k) / fact(n - k)

n, m, t = map(int, raw_input().split())
answer = 0
for mantakes in range(4, n + 1):
    femaletakes = t - mantakes
    if femaletakes < 1:
        continue
    variants = calcC(n, mantakes) * calcC(m, femaletakes)
    answer += variants
print answer
