A corporate security checkpoint issues entry credentials to a line of employees each morning. Every employee needs exactly one of two credential types, labeled 0 or 1. A kiosk holds a fixed stack of credentials to dispense today, also labeled 0 or 1, ordered from the one on top (dispensed first) to the one at the bottom (dispensed last).

Employees stand in a line. Repeatedly, the kiosk offers the credential currently on top of its stack to the employee at the front of the line:

• If that employee's required type matches the offered credential, the employee takes it (the credential is removed from the stack) and leaves the line.
• Otherwise, the employee steps out of the front position and rejoins the line at the very back, without taking anything.

This continues until either the kiosk runs out of credentials, or every employee still in line has been offered the current top credential once already without a single match -- meaning a full lap of the remaining line has passed with nobody taking it -- at which point the process halts for the day.

Given the line order and the stack order, determine how many employees end the day without a credential.

Input format

Line 1: a single integer n. Line 2: n integers, each 0 or 1 -- the employees' required credential types, listed from the front of the line to the back. Line 3: n integers, each 0 or 1 -- the credential stack, listed from the top (dispensed first) to the bottom (dispensed last).

Output format

A single integer -- the number of employees who never receive a credential.

Constraints

• 1 <= n <= 100
• Each value on lines 2 and 3 is 0 or 1.

4
0 1 0 1
0 1 0 1

0

6
1 1 1 0 0 1
1 0 0 0 1 1

3