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.io.*;
public class Main {
      static class pair implements Comparable<pair>{
        int x;
        int y;
        public pair(int x, int y){
            this.x=x;
            this.y=y;
        }
        public int compareTo(pair p){
            return (x-p.x==0)?p.y-y:x-p.x;
        }
    }
  public static void main(String[] args) throws IOException,InterruptedException{
	BufferedReader	 br = new BufferedReader(new InputStreamReader(System.in));
	PrintWriter out = new PrintWriter(System.out);
     	// String s = br.readLine();
        // char[] arr=s.toCharArray();
        // ArrayList<Integer> arrl = new ArrayList<Integer>(); 
        // TreeSet<Integer> ts1 = new TreeSet<Integer>(); 
        // HashSet<Integer> h = new HashSet<Integer>(); 
        // HashMap<Integer, Integer> map= new HashMap<>(); 
        // PriorityQueue<String> pQueue = new PriorityQueue<String>(); 
        // LinkedList<String> object = new LinkedList<String>(); 
        // StringBuilder str = new StringBuilder(); 
 	    StringTokenizer   st = new StringTokenizer(br.readLine());
 	      int n = Integer.parseInt(st.nextToken());
 	      int a = Integer.parseInt(st.nextToken());
 	      int b = Integer.parseInt(st.nextToken());
 	      int ans = Math.min(b+1,n-a);
 	      out.println(ans);
 	     
       	out.flush();
 
	}}