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.StringTokenizer;

public class Q131C implements Runnable {
    private void solve() throws IOException {
        int n = nextInt();
        int m = nextInt();
        int c = nextInt();

        long[][] tri = triangle();
        long sum=0;

        for(int i =4;i<=n;i++){
            for(int j =1;j<=m;j++){
                if(j+i==c){
                    long nn = tri[n+1][i+1];
                    long mm = tri[m+1][j+1];
                    sum+=nn*mm;
                }
            }
        }
        writer.print(sum);

    }


    long[][] triangle() {
        long[][] pascal = new long[31 + 1][];

        // initialize first row
        pascal[1] = new long[1 + 2];
        pascal[1][1] = 1l;

        // fill in Pascal's triangle
        for (int i = 2; i <= 31; i++) {
            pascal[i] = new long[i + 2];
            for (int j = 1; j < pascal[i].length - 1; j++)
                pascal[i][j] = pascal[i - 1][j - 1] + pascal[i - 1][j];
        }

        return pascal;
    }

    public static void main(String[] args) {
        new Q131C().run();
    }

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter writer;

    public void run() {
        try {
            boolean oj = System.getProperty("ONLINE_JUDGE") != null;
            reader = oj ? new BufferedReader(new InputStreamReader(System.in)) :
                    new BufferedReader(new FileReader(new File("input.txt")));
            tokenizer = null;
            writer = new PrintWriter(System.out);
            long start = System.currentTimeMillis();
            solve();
            reader.close();
            if (!oj) writer.print("\nTime: " + (System.currentTimeMillis() - start) + "\n");
            writer.close();
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

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

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

    String nextToken() throws IOException {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }
}
