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 class C implements Runnable {
    private MyScanner in;
    private PrintWriter out;

    private void solve() {
        long[][] c = new long[31][31];
        for (int i = 0; i < 31; ++i) {
            c[i][0] = 1;
        }
        for (int i = 1; i < 31; ++i) {
            for (int j = 1; j <= i; ++j) {
                c[i][j] = c[i - 1][j] + c[i - 1][j - 1];
            }
        }
        int n = in.nextInt();
        int m = in.nextInt();
        int t = in.nextInt();
        long ans = 0;
        for (int i = Math.max(4, t - m); i <= Math.min(t - 1, n); ++i) {
            ans += c[n][i] * c[m][t - i];
        }
        out.println(ans);
    }

    @Override
    public void run() {
        in = new MyScanner();
        out = new PrintWriter(System.out);
        solve();
        in.close();
        out.close();
    }

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

    static class MyScanner {
        private BufferedReader br;
        private StringTokenizer st;

        public MyScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        public void close() {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        private String nextToken() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                    return null;
                }
            }
            return st.nextToken();
        }

        public String nextLine() {
            try {
                return br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
                return null;
            }
        }

        public String next() {
            return nextToken();
        }

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

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

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