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 Main {

    public boolean[][] memo;

    private long combination(int t, int c) {
        long sum = 1;
        for (int x = t - c + 1; x <= t; x++) {
            sum *= x;
        }
        for (int x = 2; x <= c; x++) {
            sum /= x;
        }
        return sum;
    }

    private long sum(int b, int bp, int g, int gp, int p) {
        long sum = 0;
        if (bp + gp == p && bp <= b && gp <= g && !memo[bp][gp]) {
            sum += combination(b, bp) * combination(g, gp);
            memo[bp][gp] = true;
            return sum;
        } else if (bp + gp <= p && bp <= b && gp <= g) {
            sum += sum(b, bp + 1, g, gp, p);
            sum += sum(b, bp, g, gp + 1, p);
            return sum;
        } else {
            return sum;
        }
    }

    private void solve() throws IOException {
        int[][] c = new int[40][40];
        for (int x = 0; x <= 30; x++) {
            c[x][0] = c[x][x] = 1;
            for (int y = 1; y <= x; y++) {
                c[x][y] = c[x - 1][y - 1] + c[x - 1][y];
            }
        }

//        for (int x = 0 ; x < 31; x++) {
//            for (int y = 0; y < 31; y++) {
//                System.out.print(c[x][y] + " ");
//            }
//            System.out.println();
//        }

        int n = nextInt(), m = nextInt(), t= nextInt();
        long ans  = 0;
        for (int x = 4; x <=n; x++) {
            int p = t - x;
            if (p < 1) {
                break;
            }
            if (p > m){
                continue;
            }
            ans += (long)((long)c[n][x] * (long)c[m][p]);
        }
        System.out.println(ans);
    }

    public static void main(String[] args) {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            new Main().solve();
            out.close();
        } catch (Throwable e) {
            System.out.println(e);
            System.exit(239);
        }
    }
    static BufferedReader br;
    static StringTokenizer st;
    static PrintWriter out;

    static String nextToken() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            String line = br.readLine();
            if (line == null) {
                return null;
            }
            st = new StringTokenizer(line);
        }
        return st.nextToken();
    }

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

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

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

    static int[] nextIntArray(int n) throws IOException {
        int[] temp = new int[n];
        for (int x = 0; x < n; x++) {
            temp[x] = nextInt();
        }
        return temp;
    }

    static long[] nextLongArray(int n) throws IOException {
        long[] temp = new long[n];
        for (int x = 0; x < n; x++) {
            temp[x] = nextLong();
        }
        return temp;
    }

    static String[] nextArray(int n) throws IOException {
        String[] temp = new String[n];
        for (int x = 0; x < n; x++) {
            temp[x] = nextToken();
        }
        return temp;
    }
}
