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.StringTokenizer;

public class PetrsPotition {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		BufferedReader entrada = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer linea = new StringTokenizer(entrada.readLine());
		
		int n=Integer.parseInt(linea.nextToken()),a=Integer.parseInt(linea.nextToken()),b=Integer.parseInt(linea.nextToken());
		int cont=0;
		for (int i = 1; i <= n; i++) {
			if(i-1>=a && n-i<=b) cont++;
		}
		System.out.println(cont);
	}

}
