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
import java.io.*;
import java.util.*;
public final class world_is_theatre
{
    static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static FastScanner sc=new FastScanner(br);
    static PrintWriter out=new PrintWriter(System.out);
	static long[][] dp;
	
	static void build()
	{
		dp=new long[31][31];
		for(int i=1;i<31;i++)
		{
			dp[i][1]=i;
		}
		for(int j=2;j<31;j++)
		{
			dp[j][j]=1;
			for(int i=j+1;i<31;i++)
			{
				dp[i][j]=dp[i-1][j]+dp[i-1][j-1];
			}
		}
	}
	
	public static void main(String args[]) throws Exception
	{
		build();
		int n=sc.nextInt(),m=sc.nextInt(),t=sc.nextInt();
		long ans=0;
		for(int i=4;i<=t-1;i++)
		{
			if(i<=n && t-i<=m)
			{
				ans=ans+(dp[n][i]*dp[m][t-i]);
			}
		}
		out.println(ans);
		out.close();
	}
}
class FastScanner
{
    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }
	
    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
	
	public String next() throws Exception {
		return nextToken().toString();
	}
	
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}