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
from math import factorial

#   We don't have to take care of girls, since exact t members are required.
#
#   if both are greater i.e. n,m > t
#   for choosing boys, start with choosing 4 boys to t-1 boys
#   
#   if n >= t >= m
#   for choosing boys, start with choosing 4 boys to t-1 boys
#   
#   if m >= t >= n
#   for choosing boys, start with choosing 4 boys to n boys
#   
#   if t > m,n
#   for choosing boys, start with choosing 4 boys to n boys

def solve():
    n, m, t = list(map(int, str(raw_input()).split()))
    min_boys = max(4, t-m)
    max_boys = min(t-1, n)
    total = 0
    for i in range(min_boys, max_boys+1):
        g = t-i
        nCi = factorial(n)/(factorial(i)*factorial(n-i))
        mCg = factorial(m)/(factorial(g)*factorial(m-g))
        total += nCi*mCg
    print total

solve()
