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.IOException;
import java.io.InputStreamReader;

public class TheNumberOfPositions {

    public static void main( final String[] args ) throws IOException {
        final BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );
        final String[] nab = br.readLine().split( " " );
        final int n = Integer.parseInt( nab[ 0 ] );
        final int a = Integer.parseInt( nab[ 1 ] );
        final int b = Integer.parseInt( nab[ 2 ] );

        int res = 0;
        for ( int i = 1; i <= n; ++i ) {
            if ( i > a && n - b <= i ) {
                ++res;
            }
        }
        System.out.println( res );
    }

}
