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.*;
public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] input = reader.readLine().split(" ");
        int numOfPeople = Integer.parseInt(input[0]);
        int a = Integer.parseInt(input[1]);
        int b = Integer.parseInt(input[2]);
        int c = 0;
        for(int i=a+1;i<=numOfPeople;++i) {
            if(numOfPeople-i<=b) {
                ++c;
            }   
        }
        System.out.println(c);
    }
}