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
/**
 * Created by Karan Jobanputra on 29-05-2017.
 */


import java.util.Scanner;
import java.io.*;
import java.util.*;
import java.math.*;
import java.lang.*;

import static java.lang.Math.*;

public class Main {
    public static long C(long n,long m)
    {
        BigInteger mul = new BigInteger("1");
        BigInteger div = new BigInteger("1");
       // System.out.println(n+"C"+m);
        if(n==0 || m==0) return 1;
        if(m>n) return 0;
        m = min(m,n-m);
        for(int i=0;i<m;i++)
        {
            mul = mul.multiply(new BigInteger(""+(n-i)));
            div = div.multiply (new BigInteger(""+(i+1)));
        }
        long a = mul.divide(div).longValueExact();
        //System.out.println(a);
        return a;
    }
    public static void main(String args[]) throws Exception {
        InputReader sc = new InputReader(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        long n = sc.nextLong();
        long m = sc.nextLong();
        long t = sc.nextLong();
        if(n+m == t)
        {
            pw.println(1);
            pw.close();
            return;
        }
        if(n<4 || m<1 || t<5)
        {
            pw.println("0");
            pw.close();
            return;
        }
        long sum = 0;
        for(long i=4;i<=t-1;i++)
        {
            sum += C(n,i)*C(m,t-i);
            //pw.println("I="+i+"Sum="+sum);
        }
        pw.println(sum);
        pw.close();
    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public String nextLine() {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    static class Node implements Comparable<Node> {
        int v;
        int w;

        Node(int v, int w) {
            this.v = v;
            this.w = w;
        }

        public int compareTo(Node node) {
            if (w == node.w)
                return Integer.compare(v, node.v);

            return (-1) * Integer.compare(w, node.w);
        }
    }
}