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.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Scanner;

public class Main {
    /*static boolean isDistinct(Integer x){
        boolean res = false;
        String s = x.toString();
        return s.charAt(0) != s.charAt(1) && s.charAt(0) != s.charAt(2) && s.charAt(0) != s.charAt(3)
                && s.charAt(1) != s.charAt(2) && s.charAt(1) != s.charAt(3) && s.charAt(2) != s.charAt(3);
    }*/
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        /*int n = scanner.nextInt(),k=scanner.nextInt();
        int ans=10000;
        for (int i = 0; i <= n; i++) {
            for (int j = 0; j <= n; j++) {
                for (int l = 0; l <= n; l++) {
                    int d = n-i-j-l;
                    if(d<0)continue;
                    long tmpK=i*5+j*4+l*3+d*2;
                    if(tmpK==k)ans = Math.min(ans,d);
                }
            }

        }
        System.out.println(ans);*/
        int n = scanner.nextInt(),a = scanner.nextInt(),b = scanner.nextInt();
        System.out.println(Math.min(n-a,b+1));
    }
}

