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.
/*
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 */


import java.io.*;

/**
 *
 * @author sousnake
 */
public class prob11 {
    public static void main(String arg[]) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s[] = br.readLine().split(" ");
        int N = Integer.parseInt(s[0]);
        int A = Integer.parseInt(s[1]);
        int B = Integer.parseInt(s[2]);
        int ans = Math.min(N-A, B+1);
        System.out.println(ans);
    }
}
