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 rec(x):
    mult=1
    i=x
    while i>=1:
        mult=mult*i
        i=i-1
    return mult
p=input().split()
n=int(p[0])
m=int(p[1])
t=int(p[2])
r=t-4
s=0
if r<=m:
    i=4
    j=r
    while i<=n and j>=1:
        s=s+(rec(n)//(rec(i)*rec(n-i)))*(rec(m)//(rec(j)*rec(m-j)))
        i=i+1
        j=j-1
    print(s)
else:
    j=m
    i=t-m
    while i<=n and j>=1:
        s=s+(rec(n)//(rec(i)*rec(n-i)))*(rec(m)//(rec(j)*rec(m-j)))
        i=i+1
        j=j-1
    print(s)
