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.*;
import java.math.*;
import java.io.*;
import java.util.Collections;

public class Solution {

    static class Solver {

        Solver() {
        }

        public void solve(FastScanner sc, PrintWriter out) throws IOException {
            int n = sc.nextInt();
            int a = sc.nextInt();
            int b = sc.nextInt();

            n -= a;
            if(n == b+1) {
                out.println(n);
            } else if(b+1 < n) {
                out.println(b+1);
            } else {
                out.println(n);
            }
            out.flush();
        }
    } 


    
    public static void main(String[] args) throws IOException{
        FastScanner scanner = new FastScanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        (new Solver()).solve(scanner, out);
        out.flush();

    }

    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStream stream) {
            try {
                br = new BufferedReader(new InputStreamReader(stream));
            } catch(Exception e) {
                e.printStackTrace();
            }
        }

        boolean hasNextToken() {
            if(st == null) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch(IOException e) {
                    
                }
            }
            return st.hasMoreTokens();
        } 

        String next() {
            while(st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch(IOException e) {
                    e.printStackTrace();
                }
            }

            return st.nextToken();
        }

        String nextLine() throws IOException{
            return br.readLine();
        }

        byte nextByte() {
            return Byte.parseByte(next());
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

    }

}

