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.IOException;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;




public class Main {
	public static void main(String[] args) throws IOException{
    		Reader.init(System.in);
    int n,a,b;
    n=Reader.nextInt();
    a=Reader.nextInt();
    b=Reader.nextInt();
    
    if(a+b>=n-1){
    	System.out.println((int)(n-a));
    }
    else
    {
    	System.out.println((int)(b+1));
    }
    		
	}
	
		
	
	
	
        static class Reader {
            static BufferedReader reader;
            static StringTokenizer tokenizer;

            
            static void init(InputStream input) {
                reader = new BufferedReader(
                             new InputStreamReader(input) );
                tokenizer = new StringTokenizer("");
            }

            
            static String next() throws IOException {
                while ( ! tokenizer.hasMoreTokens() ) {
                    
                    tokenizer = new StringTokenizer(
                           reader.readLine() );
                }
                return tokenizer.nextToken();
            }
            
            
            static String nextLine() {
              String line="";
			try {
				line = reader.readLine();
			} catch (IOException e) {
			
				e.printStackTrace();
			}
              return  line;
            }

            static int nextInt() throws IOException {
                return Integer.parseInt( next() );
            }
            
            static long nextLong() throws IOException {
                return Long.parseLong( next() );
            }
            
            static double nextDouble() throws IOException {
                return Double.parseDouble( next() );
            }
                   }
    
        
        
        
}

