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.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class TheWorldIsATheatre {

    static final int MAX = 61;
    static long[][] comb;

    static void preprocess() {
	comb = new long[MAX][MAX];
	comb[0][0] = 1;
	for (int i = 1; i < MAX; i++) {
	    comb[i][0] = 1;
	    for (int j = 1; j < MAX; j++)
		comb[i][j] = comb[i - 1][j - 1] + comb[i - 1][j];
	}
    }

    public static void main(String[] args) throws IOException {
	MyScanner sc = new MyScanner(System.in);
	preprocess();
	int n = sc.nextInt(), m = sc.nextInt(), t = sc.nextInt();
	long ans = 0;
	for (int i = t - 1; i >= 4; i--) {
	    ans += comb[n][i] * comb[m][t - i];
	}
	System.out.println(ans);
    }

    static class MyScanner {
	StringTokenizer st;
	BufferedReader br;

	public MyScanner(InputStream s) {
	    br = new BufferedReader(new InputStreamReader(s));
	}

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

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

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

	public String nextLine() throws IOException {
	    return br.readLine();
	}

	public boolean ready() throws IOException {
	    return br.ready();
	}
    }
}
