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 A {
    
    
    public static void main(String... args) {
        
        Scanner sc = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        
        
        int n = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
        
        // there can be more but not less people who are standing in front of him i.e (a >= a)
        // there can be less but not more people who are standing behind him i.e (b <= b)
        
        
        if(a + b >= n) {
            out.println(n - a);
        }
        else {
            
            int sum = a + b;
            int diff = n - sum;
            
            diff--;
            
            out.println(n - a - diff);
        }
        
        
        out.flush();
        out.close();
    }
}