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.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Theatre {
	public static Scanner sc = new Scanner(System.in);
	public static StringTokenizer st;
	public static PrintWriter pw = new PrintWriter(System.out);
	final static boolean debugmode = true;
	public static int k = 7; // for 10^9 + k mods.
	public static long STMOD = 1000000000 + k; // 10^9 + k
	public static void main(String[] args) {
		int boys = getInt();
		int girls = getInt();
		int actors = getInt();
		long[][] choose = new long[70][70];
		for(int i = 1;i<70;i++){
			choose[i][0] = 1;
			for(int j = 1;j<=i;j++){
				choose[i][j] = choose[i][j-1] *(i-(j-1))/((j-1)+1);
				
			}
		}
		
		long ways = 0;
		for (int aboys = 4;aboys < actors;aboys++){
			int agirls = actors-aboys;
			//System.out.println(aboys + " "+agirls);
			ways += choose[boys][aboys] * choose[girls][agirls];
		}
		System.out.println(ways);
	}
	public static void debug(String toPrint){
		if(!debugmode) {return;}
		pw.println("[DEBUG]: "+toPrint);
	}
	public static void  submit(int[] k){
		pw.println(Arrays.toString(k));
		pw.close();
	}
	public static void submit(int p){
		pw.println(Integer.toString(p));
		pw.close();
	}
	public static void submit(String k){
		pw.println(k);
		pw.close();
	}
	public static void submit(double u){
		pw.println(Double.toString(u));
		pw.close();
	}
	public static void submit(long lng){
		pw.println(Long.toString(lng));
		pw.close();
		
	}
	public static int getInt(){
		if (st != null && st.hasMoreTokens()){
			return Integer.parseInt(st.nextToken());
		}
		st = new StringTokenizer(sc.nextLine());
		return Integer.parseInt(st.nextToken());
	}
	public static long getLong(){
		if (st != null && st.hasMoreTokens()){
			return Long.parseLong(st.nextToken());
		}
		st = new StringTokenizer(sc.nextLine());
		return Long.parseLong(st.nextToken());
	}
	public static double getDouble(){
		if (st != null && st.hasMoreTokens()){
			return Double.parseDouble(st.nextToken());
		}
		st = new StringTokenizer(sc.nextLine());
		return Double.parseDouble(st.nextToken());
	}
	public static String getString(){
		if(st != null && st.hasMoreTokens()){
			return st.nextToken();
		}
		st = new StringTokenizer(sc.nextLine());
		return st.nextToken();
	}
	public static String getLine(){
		return sc.nextLine();
	}
	public static int[][] readMatrix(int lines,int cols){
		int[][] matrr = new int[lines][cols];
		for (int i = 0;i < lines;i++){
			for(int j = 0;j < cols;j++){
				matrr[i][j] = getInt();
			}
		}
		return matrr;
	}
	public static int[] readArray(int lines){
		int[] ar = new int[lines];		
		for (int i = 0;i<lines;i++) ar[i] =getInt();
		return ar;
	}
	
}
