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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String[] linea = br.readLine().split(" ");
        int num = Integer.parseInt(linea[0]);
        int num2 = Integer.parseInt(linea[1]);
        int num3 = Integer.parseInt(linea[2]);

        if (num2 + num3 < num) {
            System.out.println(num3 + 1);
        }else if(num3 + num2 == num){
            System.out.println(num3);
        }else{
            System.out.println(num-num2);
        }
    }
}