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 bin(n, k):
    if k == 0:
        return 1
    if k > n - k:
        return bin(n, n-k)
    num, den = 1,1
    for i in xrange(k):
        num *= (n - i)
        den *= (i+1)
    return num / den

n, m, t = map(int, raw_input().split())

s = 0
mxb = min(t-5,n-4)
mxg = min(t-5,m-1)
mnb = max(0,t-m-4) # !
mng = max(0,t-n-1) # !
b = 0 if mxb >= mxg else 1

if not b:
    for i in range(mng, mxg+1):
        tmp = bin(m, 1+i) * bin(n, t - 1 - i)
        s += tmp
else:
    for i in range(mnb, mxb+1):
        tmp = bin(n,4+i) * bin(m, t - 4 - i)
        s += tmp
print s
                    
