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.*;
import java.io.*;
import java.lang.*;

public class Main {
	
	static int INF = 1000000000;
	static int MAXN = 31;
	static long[][] c = new long[MAXN][MAXN];
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		int n, m, t;
		n = input.nextInt();
		m = input.nextInt();
		t = input.nextInt();
		init();
		long res = 0;
		for (int i = 4; i <= t - 1; ++i) {
			if (i <= n && t - i <= m) {
				res += c[n][i] * c[m][t - i];
			//	System.out.println(c[n][i] + " " + c[m][t - i] + " " + res);
			}
		}
		System.out.println(res);
	}	
	
	static void init() {				
		for (int i = 0; i < MAXN; ++i) {
			for (int k = 0; k < MAXN; ++k) {
				c[i][k] = 0;
			}
		}
		for (int i = 0; i < MAXN; ++i) {
			c[i][0] = 1;
		}
		for (int i = 1; i < MAXN; ++i) {
			for (int k = 1; k <= i; ++k) {
				c[i][k] = c[i - 1][k] + c[i - 1][k - 1];
			}
		}
	}
}