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 Task131C {
	
	PrintWriter out;
	BufferedReader input;
	Task131C() {
		input = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out,true);
		try {
			solver();
		} catch(Exception ex) {
			System.err.println(ex.getClass().getName() + " Cause: " + ex.getMessage());
		} finally {
			out.close();
			try {
				input.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	StringTokenizer st = new StringTokenizer("");
	private String nextToken() throws IOException{
		while (!st.hasMoreElements()) {
			st = new StringTokenizer(input.readLine());
		}
		return st.nextToken();
	}
	private int nextInt() throws IOException{
		return Integer.parseInt(nextToken());
	}
	long fact(long n) {
		long res = 1;
		for (int i = 1; i <= n; i++) {
			res *= i;
		}
		return res;
	}
	public void solver() throws IOException{
		int n = nextInt();
		int m = nextInt();
		int t = nextInt();
		
		long[][] c = new long[61][61];
		
		for (int i = 0; i < 61; i++) {
			for (int j = 0; j <= i; j++) {
				if (j == 0) {
					c[i][j] = 1;
				} else {
					c[i][j] = c[i-1][j-1] + c[i-1][j];
				}
			}
		}
		
		long res = 0;
		int st = t;
		while(t != 4) {
			t--;
			int g = st - t;
			res += c[n][t] * c[m][g];
		}
		System.out.println(res);
		
	}

	public static void main(String[] args) {
		new Task131C();
	}

}
