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.security.KeyStore.Entry;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.*;
import java.io.*;



public class temp {
	public static void main(String[] args) throws IOException,InterruptedException {BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		int a = Integer.parseInt(st.nextToken());
		int b = Integer.parseInt(st.nextToken());
		
		int positions = 0;
		int current = a+1;
		while(current<=n)
		{
			if(current>=(n-b))
				positions++;
			current++;
		}
		System.out.println(positions);
	}
}


