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.math.*;
import java.util.*;
@SuppressWarnings("Duplicates")
// author @mdazmat9
public class Main{
    static Scanner sc = new Scanner(System.in);
    static PrintWriter out = new PrintWriter(System.out);
    public static void main(String[] args) throws IOException {
        int test = 1;
      //  test=sc.nextInt();
        for (int ind = 0; ind < test; ind++) {
            solve();
        }
        out.flush();
    }
 
    static void solve() {
        int n=sc.nextInt();
        int m=sc.nextInt();
        int t=sc.nextInt();
 
        BigInteger[] fact=new BigInteger[31];
        fact[0]=new BigInteger("1");
        long ans=0;
        for(int i=1;i<=30;i++)fact[i]=fact[i-1].multiply(new BigInteger(i+""));
       // out.println(fact[30]);
        for(int i=4;i<=n;i++){
            int x=i;
            int y=t-x;
            if(y<=m && y>=1){
 
                BigInteger mul=fact[x].multiply(fact[n-x]);
                BigInteger ans1=fact[n].divide(mul);
 
                 mul=fact[y].multiply(fact[m-y]);
                BigInteger ans2=fact[m].divide(mul);
                ans+=(Long.parseLong(ans1.toString())*Long.parseLong(ans2.toString()));
            }
        }
        out.println(ans);
    }
 
 
 
 
    static int[] intarray(int n){ int [] a=new int[n];for(int i=0;i<n;i++)a[i]=sc.nextInt();return a; }
    static void sort(int[]a){ shuffle(a);Arrays.sort(a);}
    static void sort(long[]a){ shuffle(a);Arrays.sort(a);}
    static long[] longarray(int n){ long [] a=new long[n];for(int i=0;i<n;i++)a[i]=sc.nextLong();return a; }
    static ArrayList<Integer> intlist(int n){ArrayList<Integer> list=new ArrayList<>();for(int i=0;i<n;i++)list.add(sc.nextInt());return list; }
    static ArrayList<Long> longlist(int n){ArrayList<Long> list=new ArrayList<>();for(int i=0;i<n;i++)list.add(sc.nextLong());return list; }
    static int[][] int2darray(int n,int m){ int [][] a=new int[n][m];for(int i=0;i<n;i++){ for(int j=0;j<m;j++){ a[i][j]=sc.nextInt(); } }return a; }
    static long[][] long2darray(int n,int m){ long [][] a=new long[n][m];for(int i=0;i<n;i++){ for(int j=0;j<m;j++){ a[i][j]=sc.nextLong(); } }return a; }
    static char[][] char2darray(int n,int m){ char [][] a=new char[n][m];for(int i=0;i<n;i++){ String s=sc.next(); a[i]=s.toCharArray(); }return a; }
 
    static double pi=3.14159265358979323846264;
    public static double logb( double a, double b ) {return Math.log(a) / Math.log(b); }
    static long fast_pow(long a, long b,long abs) {
        if(b == 0) return 1L;
        long val = fast_pow(a, b / 2,abs);
        if(b % 2 == 0) return val * val % abs;
        else return val * val % abs * a % abs;
    }
    static long abs = (long)1e9 + 7;
    static   void shuffle(int[] a) { int n = a.length;for(int i = 0; i < n; i++) { int r = i + (int) (Math.random() * (n - i));int tmp = a[i];a[i] = a[r];a[r] = tmp; } }
    static   void shuffle(long[] a) { int n = a.length;for(int i = 0; i < n; i++) { int r = i + (int) (Math.random() * (n - i));long tmp = a[i];a[i] = a[r];a[r] = tmp; } }
    static long gcd(long a , long b) {
        if(b == 0) return a;
        return gcd(b , a % b);
    }
}
 
class Scanner {
    public BufferedReader reader;
    public StringTokenizer st;
    public Scanner(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        st = null;
    }
    public String next() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                String line = reader.readLine();
                if (line == null) return null;
                st = new StringTokenizer(line);
            } catch (Exception e) {
                throw (new RuntimeException());
            }
        }
        return st.nextToken();
    }
    public int nextInt() {
        return Integer.parseInt(next());
    }
    public long nextLong() {
        return Long.parseLong(next());
    }
    public double nextDouble() {
        return Double.parseDouble(next());
    }
}
class DSU {
 
    int[] rank, parent;
    int n;
 
    public DSU(int n) {
        rank = new int[n];
        parent = new int[n];
        this.n = n;
        makeSet();
    }
 
    void makeSet() {
        for (int i = 0; i < n; i++)
            parent[i] = i;
    }
    int find(int x) {
        if (parent[x] != x) {
            return find(parent[x]);
        }
        return x;
    }
    void union(int x, int y) {
        int xRoot = find(x);
        int yRoot = find(y);
        if (xRoot == yRoot)
            return;
 
        if (rank[xRoot] < rank[yRoot])
            parent[xRoot] = yRoot;
 
        else if (rank[yRoot] < rank[xRoot])
            parent[yRoot] = xRoot;
 
        else
        {
            parent[yRoot] = xRoot;
            rank[xRoot] = rank[xRoot] + 1;
        }
    }
}