import java.util.*;

public class encontro {
    public static void main( String[] args ){
        Scanner scanner = new Scanner(System.in);
        int l = 1, r = 31; 
        for( int i = 0; i < 3; i++ ){
            int a = scanner.nextInt(), b = scanner.nextInt();
            l = Math.max( l, a ); 
            r = Math.min( r, b );
        }
        scanner.close();

        System.out.println(Math.max(0, r - l + 1));
    }
}