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.InputStreamReader;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.InputStream;
import java.util.ArrayList;

public class LightOJ {

        public static void main(String[] args) {
                InputStream inputStream = System.in;
                OutputStream outputStream = System.out;
                InputReader in = new InputReader(inputStream);
                PrintWriter out = new PrintWriter(outputStream);
                TaskA solver = new TaskA();
                solver.solve(1, in, out);
                out.close();
        }
}

class TaskA {

    int boys, girls, team;
    long ans;
    
    ArrayList<Integer> boyTeamMates = new ArrayList<>();
    ArrayList<Integer> girlTeamMates = new ArrayList<>();
    
    public void solve(int caseNum, InputReader in, PrintWriter out) {
        boys  = in.nextInt();
        girls = in.nextInt();
        team  = in.nextInt();
        teamFormation();
        for (int i=0;i<boyTeamMates.size();i++){
            ans += combinationGenerator(boys,boyTeamMates.get(i))*combinationGenerator(girls,girlTeamMates.get(i));
        }
        out.println(ans);
    }   
    
    public void teamFormation(){
        int boys  = 4;
        int girls = team - boys;
        while (boys<=this.boys){
            if (girls<=this.girls && girls>=1){
                boyTeamMates.add(boys);
                girlTeamMates.add(girls);
            }
            boys++;
            girls = team - boys;
        }
    }
    
    public long combinationGenerator(int n, int r){
        long upper;
        int i = 1;
        upper = 1;
        
        
        while (n>r){
            upper *= n;
            n--;
            upper /= i;
            i++;
        }
        
        return upper;
    }
}

class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;
 
    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
    }
 
    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }
 
    public int nextInt() {
        return Integer.parseInt(next());
    } 
    
    public Long nextLong() {
        return Long.parseLong(next());
    }
    
}
