Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1


Output

2


Input

5 2 3


Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.

import java.util.*;
import java.lang.*;
import java.io.*;
 
 
public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		FastReader sc =new FastReader();
		
	    int n,a,b;
	    n=sc.nextInt();
	    a=sc.nextInt();
	    b=sc.nextInt();
	    
	    int ans=0;
	    
	    for(int i=0;i<n;i++)
	    {
	        if(i>=a && (n-i-1)<=b)
	        {
	            ans++;
	        }
	    }
	    System.out.println(ans);
	    
	}
	
	
	
	static class FastReader {
        BufferedReader br;
        StringTokenizer st;
 
        public FastReader()
        {
            br = new BufferedReader(
                new InputStreamReader(System.in));
        }
 
        String next()
        {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
 
        int nextInt() { return Integer.parseInt(next()); }
 
        long nextLong() { return Long.parseLong(next()); }
 
        double nextDouble()
        {
            return Double.parseDouble(next());
        }
        
        float nextFloat()
        {
            return Float.parseFloat(next());
        }
 
        String nextLine()
        {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        
        int[] readArray(int n) {
			int[] a=new int[n];
			for (int i=0; i<n; i++) a[i]=nextInt();
			return a;
		}
		
		long[] readArrayLong(int n) {
			long[] a=new long[n];
			for (int i=0; i<n; i++) a[i]=nextLong();
			return a;
		}
		
    }
    
    static boolean isPalindrome(String str)
    {
 
        // Pointers pointing to the beginning
        // and the end of the string
        int i = 0, j = str.length() - 1;
 
        // While there are characters to compare
        while (i < j) {
 
            // If there is a mismatch
            if (str.charAt(i) != str.charAt(j))
                return false;
 
            // Increment first pointer and
            // decrement the other
            i++;
            j--;
        }
 
        // Given string is a palindrome
        return true;
    }
    
    static boolean palindrome_array(int arr[], int n)
    {
        // Initialise flag to zero.
        int flag = 0;
 
        // Loop till array size n/2.
        for (int i = 0; i <= n / 2 && n != 0; i++) {
 
            // Check if first and last element are different
            // Then set flag to 1.
            if (arr[i] != arr[n - i - 1]) {
                flag = 1;
                break;
            }
        }
 
        // If flag is set then print Not Palindrome
        // else print Palindrome.
        if (flag == 1)
            return false;
        else
            return true;
    }
    
	static boolean allElementsEqual(int[] arr,int n)
	{
	    int z=0;
	        for(int i=0;i<n-1;i++)
		    {
		        if(arr[i]==arr[i+1])
		        {
		            z++;
		        }
		    }
		    if(z==n-1)
		    {
		        return true;
		    }
		    else
		    {
		        return false;
		    }
		    
	}
	
	static boolean allElementsDistinct(int[] arr,int n)
	{
	    int z=0;
	        for(int i=0;i<n-1;i++)
		    {
		        if(arr[i]!=arr[i+1])
		        {
		            z++;
		        }
		    }
		    if(z==n-1)
		    {
		        return true;
		    }
		    else
		    {
		        return false;
		    }
		    
		    
	}
	
	public static void reverse(int[] array)
    {
  
        // Length of the array
        int n = array.length;
  
        // Swaping the first half elements with last half
        // elements
        for (int i = 0; i < n / 2; i++) {
  
            // Storing the first half elements temporarily
            int temp = array[i];
  
            // Assigning the first half to the last half
            array[i] = array[n - i - 1];
  
            // Assigning the last half to the first half
            array[n - i - 1] = temp;
        }
    }
	
	static boolean isSorted(int[] a)
    {
        for (int i = 0; i < a.length - 1; i++)
        {
            if (a[i] > a[i + 1]) {
                return false;
            }
        }
 
        return true;
    }
    
    static boolean isReverseSorted(int[] a)
    {
        for (int i = 0; i < a.length - 1; i++)
        {
            if (a[i] < a[i + 1]) {
                return false;
            }
        }
 
        return true;
    }
    
    static int[] rearrangeEvenAndOdd(int arr[], int n)
    {
        ArrayList<Integer> list = new ArrayList<>();
		    
		    for(int i=0;i<n;i++)
		    {
		        if(arr[i]%2==0)
		        {
		            list.add(arr[i]);
		        }
		    }
		    
		    for(int i=0;i<n;i++)
		    {
		        if(arr[i]%2!=0)
		        {
		            list.add(arr[i]);
		        }
		    }
		    int len = list.size();
		    int[] array = list.stream().mapToInt(i->i).toArray();
		    return array;
    }
    
    static long[] rearrangeEvenAndOddLong(long arr[], int n)
    {
        ArrayList<Long> list = new ArrayList<>();
		    
		    for(int i=0;i<n;i++)
		    {
		        if(arr[i]%2==0)
		        {
		            list.add(arr[i]);
		        }
		    }
		    
		    for(int i=0;i<n;i++)
		    {
		        if(arr[i]%2!=0)
		        {
		            list.add(arr[i]);
		        }
		    }
		    int len = list.size();
		    long[] array = list.stream().mapToLong(i->i).toArray();
		    return array;
    }
	
	
    
    static boolean isPrime(int n)
    {
 
        // Check if number is less than
        // equal to 1
        if (n <= 1)
            return false;
 
        // Check if number is 2
        else if (n == 2)
            return true;
 
        // Check if n is a multiple of 2
        else if (n % 2 == 0)
            return false;
 
        // If not, then just check the odds
        for (int i = 3; i <= Math.sqrt(n); i += 2)
        {
            if (n % i == 0)
                return false;
        }
        return true;
    }
    
    static int getSum(int n)
    {    
        int sum = 0;
          
        while (n != 0)
        {
            sum = sum + n % 10;
            n = n/10;
        }
      
    return sum;
    }
    
    static int gcd(int a, int b)
    {
      if (b == 0)
        return a;
      return gcd(b, a % b);
    }
     
    static long gcdLong(long a, long b)
    {
        // Everything divides 0
        if (a == 0)
          return b;
        if (b == 0)
          return a;
      
        // base case
        if (a == b)
            return a;
      
        // a is greater
        if (a > b)
            return gcdLong(a-b, b);
        return gcdLong(a, b-a);
    }
    
    static void swap(int[] arr, int i, int j)
    {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
	
	static int countDigit(long n)
    {
        return (int)Math.floor(Math.log10(n) + 1);
    }
	
}