CodeForces 131C C （组合）

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.

Sample Input

Input

5 2 5

Output

10

Input

4 3 5

Output

3
n个人，男生大于四个，女生大于一个，高中的排列组合

 #include<iostream>
 #include<cstdio>
 #include<cmath>
 typedef long long ll;
 using namespace std;
 ll fun(ll a, ll b)
 {
     ll temp=;
     for(int j=;j<=b; j++)
     {
         temp=temp*a/j;
         a--;
     }
     return temp;
 }
 int main()
 {
     ll m,n,t;
     int i,j;
     cin>>m>>n>>t;
     ll sum=;
     for(i=;i<t&&i<=m;i++)
     {
         if(t-i>=&&t-i<=t-&&t-i<=n)
             sum=sum+fun(m,i)*fun(n,t-i);
     }
     cout<<sum<<endl;
     return ;
 }