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 worldistheater {

	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		int t = scan.nextInt();
		int maxFac = Math.max(m, n);
		//		System.out.println("maxFac: " + maxFac);
		long [][] pascal = new long[maxFac + 1][maxFac + 1];
		for(int i = 0; i <= maxFac; i++) {
			for(int j = 0; j < maxFac; j++) {
				pascal[i][j] = 0; //Just to be sure.
			}
		}
		for(int i = 0; i <= maxFac; i++) {
			pascal[i][0] = 1;
		}
		for(int i = 1; i <= maxFac; i++) {
			for(int j = 1; j <= maxFac; j++) {
				pascal[i][j] = pascal[i-1][j] + pascal[i-1][j-1];
			}
		}
		long result = 0;
		for(int i = 1; i <= t - 4; i++) {
			//System.out.println(m + "!" + n + "," + i + "." + (t-i));
			if(t - i <= n && i <= m) {
				//System.out.println(i + ": " + pascal[m][i] + ", " + pascal[n][t-i]);
				result += pascal[m][i] * pascal[n][t-i];
			}
		}
		System.out.println(result);
		//		for(int i = 0; i <= maxFac; i++) {
		//			for(int j = 0; j <= maxFac; j++) {
		//				System.out.print(pascal[i][j] + " ");
		//			}
		//			System.out.println();
		//		}
	}
}
