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 fat(n):
    if n == 0:
        return 1
    else:
        return n * fat(n-1)

def partial_fat(n, k):
    res = 1
    for n in range(k+1, n+1):
        res *= n
    return res
    
def combine(n, k):
    if n < k:
        return 0
    p = max(k, n-k)
    return partial_fat(n, p) // fat(n-p)

assert(combine(5, 10) == 0)

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

possibs = 0
for d in range(4, t):
    possibs += combine(n, d) * combine(m, t-d)
print(possibs)

						    	  		  	  		  							