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.
/*
 Author: Togrul Gasimov
 Mail: ttogrul30@gmail.com 
 */


import java.util.Collection;
import java.util.Comparator;
import java.util.Locale;
import java.util.Scanner;
import java.util.Vector;
import java.util.Arrays;
import java.math.BigInteger;
import java.math.BigDecimal;
import java.util.List;
import java.util.Stack;



public class Main {

 

static double u(double x1,double y1,double x2,double y2){
return Math.sqrt( (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)  ); 
} 
static int gcd(int a,int b){
	if(b==0)return a;
	else return gcd(b,a%b);
}



// static double PI=3.1415926535897932384626433832795;

  static int[][] a = new int[100001][3];
public static void main(String[] args) {
 Scanner scan = new Scanner(System.in);
 
   int n,a,b;
   n=scan.nextInt(); a=scan.nextInt(); b=scan.nextInt();
   System.out.println(Math.min(n-a, b+1));
}
}