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=1;
    for(int j=1;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=0;
    for(i=4;i<t&&i<=m;i++)
    {
        if(t-i>=1&&t-i<=t-4&&t-i<=n)
            sum=sum+fun(m,i)*fun(n,t-i);
    }
    cout<<sum<<endl;
    return 0;
}