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.*;

// oopsies

public class C131 {
	
	static long[][] combi;
	
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int m = in.nextInt();
		int t = in.nextInt();
		int boys = 4;
		long ans = 0;
		precompute(n+m+1);
		
		while( t - boys > 0 ) {
			ans += (combi[n][boys]*combi[m][t-boys]);
			boys++;
		}
		System.out.println(ans);
	}
	
	public static void precompute(int n) {
		combi = new long[n][n];
		for( int i = 0; i < n; i++ ) {
			for( int j = 0; j <= i; j++ ) {
				if( j == 0 || j == i ) combi[i][j] = 1;
				else combi[i][j] = combi[i-1][j-1]+combi[i-1][j];
			}
		}
	}
	/* 
	public static long C( int n, int k ) {
		if( k == 0 || k == n ) return 1L;
		else return (long) C(n-1,k-1)+C(n-1,k);
	} */
}