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.*;

    public class Random2 {
        public static void main(String[] args) {
            Scanner sc=new Scanner(System.in);
            int n=sc.nextInt();
            Map<Integer,Integer> m=new HashMap<>(n);
            int a=sc.nextInt();
            int b=sc.nextInt();
            for(int i=n-b;i<=n;i++){
                m.put(i,1);
            }
            for(int i=a+1;i<=n;i++){
                if(m.containsKey(i)){
                    m.put(i,m.get(i)+1);
                }
                else
                    m.put(i,1);
            }
         //   System.out.println(m);
            Set<Integer> s=m.keySet();
            int count=0;
            for(int i:s){
                if(m.get(i)>1){
                    count++;
                }
            }
            System.out.println(count);
        }
    }