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
#precalculations 
fact = [0]*(101)
fact[0]=fact[1]=1
for i in range(2,101):
    fact[i]=fact[i-1]*i

n,m,t = map(int,input().split())
ans = 0
if(n>m):
    a = t-1
    b = 1
    while(a>=4 and b<=m):
        d = fact[n]//(fact[n-a]*fact[a])
        e = fact[m]//(fact[m-b]*fact[b])
        ans+=d*e
        a-=1;b+=1
else:
    a=4
    b=t-4  
    while(b>=1 and a<=n):
        d = fact[n]//(fact[n-a]*fact[a])
        e = fact[m]//(fact[m-b]*fact[b])
        ans+=d*e
        a+=1;b-=1
print(ans)