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.awt.*;
    import java.awt.geom.*;
    import java.io.*;
    import java.text.*;
    import java.util.*;
    import java.util.regex.*;

    public class Main{
        static class Run implements Runnable{
            //TODO parameters
            final boolean consoleIO = true;
            final String inFile = "input.txt";
            final String outFile = "output.txt";
            
            int n,m,t;
            boolean ok(long a, long b) {
                return b<=m && a >=4 && b >= 1;
            }
            
            
            HashMap<Long,Vector<Long>> p;
            long solve() {
                C(30, 30);
                long c = 0;
                
                for(int a = 4; a <= n; ++a)
                    if(ok(a,t-a))
                        c+= B[n][a]*B[m][t-a];
                
                return c;
            }
            
            long[][] B = new long[31][31];
            void C(int n, int k){
                for(int i=0;i<=n;++i) {
                   B[i][0]=1;
                   B[i][i]=1;
                   for(int j=1;j<i;++j) 
                       B[i][j]=B[i-1][j-1]+B[i-1][j];
                }
            }
            
            @Override
            public void run() {
                n = nextInt();
                m = nextInt();
                t = nextInt();
                
                print(solve());
                close();
            }
        //=========================================================================================================================
            BufferedReader in;
            PrintWriter out;
            StringTokenizer strTok;
           
            Run() {
                if (consoleIO) {
                    initConsoleIO();
                }
                else {
                    initFileIO();
                }
            }
           
            void initConsoleIO() {
                in = new BufferedReader(new InputStreamReader(System.in));
                out = new PrintWriter(new OutputStreamWriter(System.out));
            }
           
            void initFileIO() {
                try {
                    in = new BufferedReader(new FileReader(inFile));
                    out = new PrintWriter(new FileWriter(outFile));
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
           
            void close() {
                try {
                    in.close();
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
           
            int nextInt() {
                return Integer.parseInt(nextToken());
            }
           
            double nextDouble() {
                return Double.parseDouble(nextToken());
            }
           
            float nextFloat() {
                return Float.parseFloat(nextToken());
            }
           
            long nextLong() {
                return Long.parseLong(nextToken());
            }
           
            String nextLine() {
                try {
                    return in.readLine();
                } catch (IOException e) {
                    return "__NULL";
                }
            }
           
            boolean hasMoreTokens() {
                return (strTok == null) || (strTok.hasMoreTokens());
            }
           
            String nextToken() {
                while (strTok == null || !strTok.hasMoreTokens()) {
                    String line;
                    try {
                        line = in.readLine();
                        strTok = new StringTokenizer(line);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
               
                return strTok.nextToken();
            }
           
            void cout(Object o){
                System.out.println(o);
            }
           
            void print(Object o) {
                out.write(o.toString());
            }
            
            void println(Object o) {
                out.write(o.toString() + '\n');
            }
           
            void printf(String format, Object... args) {
                out.printf(format, args);
            }
           
            String sprintf(String format, Object... args) {
            return MessageFormat.format(format, args);
        }
        }
       
        static class Pair<A, B> {
            A a;
            B b;
           
            A f() {
                return a;
            }
           
            B s() {
                return b;
            }
           
            Pair(A a, B b) {
                this.a = a;
                this.b = b;
            }
           
            Pair(Pair<A, B> p) {
                a = p.f();
                b = p.s();
            }
        }
       
        public static void main(String[] args) throws IOException {
            Run run = new Run();
            Thread thread = new Thread(run);
            thread.run();
        }
    }