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.math.*;

public class Main { 
    
    static boolean FROM_FILE = false;
    
    static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
        public FastReader() { 
            if (FROM_FILE) {
                try {
                    br = new BufferedReader(new FileReader("input.txt")); 
                } catch (IOException error) {
                }   
            } else {
                br = new BufferedReader(new InputStreamReader(System.in));    
            }
        }
        String next() { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } catch (IOException  e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        }
        int nextInt() { 
            return Integer.parseInt(next()); 
        }
        long nextLong() { 
            return Long.parseLong(next()); 
        }
  
        double nextDouble() { 
            return Double.parseDouble(next()); 
        } 
        String nextLine() { 
            String str = ""; 
            try { 
                str = br.readLine(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    }
    
    static long comb(long n, long k) {
        long nCk = 1;
        for (long i = 0; i < k; i += 1) {
            nCk = nCk * (n - i) / (i + 1);
        }
        return nCk;
    }
    
    public static void main(String[] args) { 
        FastReader fr = new FastReader(); 
        PrintWriter out = null;
        if (FROM_FILE) {
            try {
                out = new PrintWriter(new FileWriter("output.txt"));
            } catch (IOException error) {
                
            }
        } else {
            out = new PrintWriter(new OutputStreamWriter(System.out));
        }
        long n = fr.nextLong(), m = fr.nextLong(), t = fr.nextLong();
        long res = 0;
        if (n >= 4 && n >= 1 && t >= 5) {
            for (long i = Math.max(4, t - m); i <= Math.min(n, t - 1); i += 1) {
                // out.println(i + " " + (t - i));
                res += comb(n, i) * comb(m, t - i);
            }
        }
        out.println(res);
        
        out.flush();
    } 
} 