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.List;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import java.util.*;

public class Watermelon {
	public static void main(String[] args) throws IOException{
		Main m=new Main();
		m.solve();
	}
	}
class Main{
	
	 BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
	 private int[] array;
	    private int[] tempMergArr;
	    private int length;
	
	    BigInteger[] temp=new BigInteger[31];
		BigInteger x,y,z;
	    StringTokenizer stringTokenizer;

	     String next() throws IOException {
	        while (stringTokenizer == null || !stringTokenizer.hasMoreTokens()) {
	            stringTokenizer = new StringTokenizer(reader.readLine());
	        }
	        return stringTokenizer.nextToken();
	    }

	    int nextInt() throws IOException {
	        return Integer.parseInt(next());
	    }

	    long nextLong() throws IOException {
	        return Long.parseLong(next());
	    }
	    void solve() throws IOException  {
	       this.fact();
	       int n=this.nextInt();
	       int m=this.nextInt();
	       int t=this.nextInt();
	       int tn=n;
	       int tm=m;
	       BigInteger sum=BigInteger.ZERO;
	       while(tn>=4){
	    	   tm=m;
	    	   while(tm>=1){
	    		  if((tn+tm)==t)
	    			  {
	  //  			  System.out.println(tn+" "+tm);
	    			  sum=(sum.add((comb(n,tn).multiply(comb(m,tm)))));
	    			  }
	    		  tm--;
	    	   }
	    	   tn--;
	       }
	       System.out.println(sum);
	  
	    }
	public BigInteger comb(int n,int r){
	     x=this.temp[n];
		 y=this.temp[r];
		 z=this.temp[n-r];
	//	 System.out.println(x+" "+y+" "+z);
		 BigInteger ret=x.divide(y.multiply(z));
		 return ret;
		 
	}
	public void fact(){
		this.temp[0]=BigInteger.ONE;
		this.temp[1]=BigInteger.ONE;
		for(int i=2;i<this.temp.length;i++){
			temp[i]=(temp[i-1].multiply(BigInteger.valueOf(i)));
		}
	}
	private static int gcd(int a, int b)
	{
	    while (b > 0)
	    {
	    	int temp = b;
	        b = a % b; // % is remainder
	        a = temp;
	    }
	    return a;
	}
	private static int lcm(int a, int b)
	{
	    return a * (b / gcd(a, b));
	}
	static int[] toFractionPos(int x,int y){
		int a=gcd(x,y);
		int[] arr={x/a,y/a};
		//display(arr);
		return arr;
	}
   
	static void display(int[][] arr){
		for(int i=0;i<arr.length;i++){
			for(int j=0;j<arr[i].length;j++){
				System.out.print(arr[i][j]+" ");
		}
			System.out.println();
		}
		System.out.println();
	}

	 static void display(String[] arr){
			for(int i=0;i<arr.length;i++){
				System.out.println(arr[i]+" ");
			}	
			//System.out.println();
		
	 }
	 static void display(int[] arr){
		 for(int i=0;i<arr.length;i++)
				System.out.print(arr[i]+" ");
		System.out.println();
		 }
		 static void display(double[] arr){
		 	   for(int i=0;i<arr.length;i++){
		 		   System.out.print(arr[i]+" ");
		 	   }
		 	   System.out.println();
	    }
	 static void display(char[] arr){
		// System.out.println();
		 int t=0;
			for(int i=0;i<arr.length;i++){
				if(arr[i]!='0'){t=i;break;}
			}	
			while(t!=arr.length){
				System.out.print(arr[t]);
				t++;
			}
			System.out.println();
		
		  }
	 static String str(char[] carr){
		 String str="";
		 for(int i=0;i<carr.length;i++){
			    str=str+carr[i];
			}
		 return str;
	 }
	    public void sort(int inputArr[]) {
	        this.array = inputArr;
	        this.length = inputArr.length;
	        this.tempMergArr = new int[length];
	        doMergeSort(0, length - 1);
	    }
	 
	    private void doMergeSort(int lowerIndex, int higherIndex) {
	         
	        if (lowerIndex < higherIndex) {
	            int middle = lowerIndex + (higherIndex - lowerIndex) / 2;
	            // Below step sorts the left side of the array
	            doMergeSort(lowerIndex, middle);
	            // Below step sorts the right side of the array
	            doMergeSort(middle + 1, higherIndex);
	            // Now merge both sides
	            mergeParts(lowerIndex, middle, higherIndex);
	        }
	    }
	 
	    private void mergeParts(int lowerIndex, int middle, int higherIndex) {
	 
	        for (int i = lowerIndex; i <= higherIndex; i++) {
	            tempMergArr[i] = array[i];
	        }
	        int i = lowerIndex;
	        int j = middle + 1;
	        int k = lowerIndex;
	        while (i <= middle && j <= higherIndex) {
	            if (tempMergArr[i] <= tempMergArr[j]) {
	                array[k] = tempMergArr[i];
	                i++;
	            } else {
	                array[k] = tempMergArr[j];
	                j++;
	            }
	            k++;
	        }
	        while (i <= middle) {
	            array[k] = tempMergArr[i];
	            k++;
	            i++;
	        }
	 
	    }
}


 class  Count implements Comparable {
    	    Integer i;
    	    Integer j;
            Integer k;
    	    Count(int i,int j){
    	        this.j=j;
    	        this.i=i;
    	        this.k=i;
    	    }
    	    void display(){
    	    	System.out.println(i+" "+j+" "+k);
    	    }
    	    
    	    	@Override
    		public int compareTo(Object o) {
    			// TODO Auto-generated method stub
    			Count c=(Count)o;
    			if(i.compareTo(c.i)>0)
    				return 1;
    			else if(i.compareTo(c.i)<0)
    				return -1;
    			else{
    				return 0;
    				
    			}
    		}
    		
    	}

 class  Counti implements Comparable {
    	    Integer i;
    	    int j;
    	    int k;
    	    Counti(int i,int j,int k){
    	        this.j=j;
    	        this.i=i;
    	        this.k=k;
    	    }
    	    void display(){
    	    	System.out.println(i+" "+j+" "+k);
    	    }
    	    
    	    	@Override
    		public int compareTo(Object o) {
    			// TODO Auto-generated method stub
    			Counti c=(Counti)o;
    			if(i.compareTo(c.i)>0)
    				return 1;
    			else if(i.compareTo(c.i)<0)
    	    		return -1;
    			else
    				return 0;
    		}
    		
    	}
		
 class Extra{
	 ArrayList<Integer> list=new ArrayList<>();
	 Extra(int i){
		 list.add(i);
	 }
	 void display(){
		 System.out.println(list.size());
		 for(int i=0;i<list.size();i++){
			 System.out.print(list.get(i)+" ");
		 }
		 System.out.println();
	 }
 }