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 TheWorldIsTheatre {

    private static long[][] comb = new long[31][31];
    static {
        for ( int i = 0; i < comb.length; ++i ) {
            comb[i][0] = 1;
            comb[i][i] = 1;
        }
        for ( int r = 2; r < comb.length; ++r ) {
            for ( int c = 1; c < r; ++c ) {
                comb[r][c] = comb[r-1][c-1] + comb[r-1][c];
            }
        }
    }

    public static void main( String[] args ) throws Exception {
        BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );
        String[] parts = br.readLine().split( " " );
        
        int b = Integer.parseInt( parts[0] ); // boys
        int g = Integer.parseInt( parts[1] ); // girls
        int t = Integer.parseInt( parts[2] ); // total
        
        long sum = 0;
        for ( int i = 4; i <= t; ++i ) {
            int tb = i;
            int tg = t - tb;
            if ( tb > b || tg > g || tg <= 0 ) continue;
            sum += comb[b][tb] * comb[g][tg];
        }
        System.out.println( sum );
    }

}
