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
n,m,t=map(int,raw_input().split())
fact=[0 for i in range(31)]
fact[0],fact[1]=1,1
ans=0
for i in range(2,31):
    fact[i]=fact[i-1]*i
i=4
k=False
while True:
    if n>=i and m>=t-i and t-i>=1:
        k=True
        ans+=(fact[n]/(fact[n-i]*fact[i]))*(fact[m]/(fact[t-i]*fact[m-t+i]))
        i+=1
    elif m<t-i:
        i+=1
    elif n<i or t-i<1:
        break
if k:
    print ans
else:
    print 1
