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.util.Scanner;


public class ProblemC {

    public static void main(String[] args) {
        new ProblemC().solve();
    }

    private void solve() {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int t = sc.nextInt();
        long[][] cnk = new long[31][31];
        cnk[0][0] = 1;
        for (int i = 1; i <= 30; i++) {
            cnk[i][0] = 1;
            for (int j = 1; j <= 30; j++) {
                cnk[i][j] = cnk[i - 1][j - 1] + cnk[i - 1][j];
            }
        }
        long ans = 0;
        for (int N = 4; N <= n; N++) {
            for (int M = 1; M <= m; M++) {
                if (N + M == t) {
                    ans += cnk[n][N] * cnk[m][M];
                }
            }
        }
        System.out.println(ans);
    }

}
