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 comb(n, r):
    num = 1
    den = 1
    i = 1
    while i <= r:
        num*=n
        den*=i
        i+=1
        n-=1
    ans = num//den
    return ans

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

ans = comb(n+m,t)

if t-3 <= m:
    ans -= comb(n,3)*comb(m,t-3)
if t-2 <= m:
    ans -= comb(n,2)*comb(m,t-2)
if t-1 <= m:
    ans -= comb(n,1)*comb(m,t-1)
if t <= m:
    ans -= comb(m,t)
if t <= n:
    ans -= comb(n,t)
print(ans)

