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.util.Arrays;
import java.util.Scanner;

public class Main {
    
    public static void main(String args[]) {
    	int n,a,b;
		Scanner in = new Scanner(System.in);
		
		n= in.nextInt(); a = in.nextInt(); b = in.nextInt();
		
		int finalpos;
		int pos1 = a + 1;
		int pos2 = n - b;
		if(pos1>pos2 || pos1 == pos2)
			finalpos = n - (a + 1) + 1;
		else
			finalpos = n - (n - b) + 1;
		
		System.out.print(finalpos);
	}	
}
	