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.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
//import java.io.FileReader; 
//import java.io.FileWriter;
//import java.lang.StringBuilder;
import java.util.StringTokenizer;
//import java.lang.Comparable;
//import java.util.Arrays;
//import java.util.HashMap;
//import java.util.ArrayList;
//import java.util.LinkedList;

public class NumberOfPosition {
    
    //static BufferedReader in = new BufferedReader(new FileReader("input.txt"));
    //static PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
    static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter out = new PrintWriter(System.out);
    //static StringBuilder sb = new StringBuilder();
    
    public static void main(String[] args) throws IOException {
        StringTokenizer st = new StringTokenizer(in.readLine());
        int n = Integer.parseInt(st.nextToken());
        int a = Integer.parseInt(st.nextToken());
        int b = Integer.parseInt(st.nextToken());
        int n1 = n - a;
        int n2 = b + 1;
        out.print(Math.min(n1, n2));
        out.close();
    }
}