Problem Statement

You are given strings S and T of length N consisting of lowercase English letters.
You can repeat the following operation any number of times (possibly zero).

• Erase the first character of S and insert the same character at any position of S.

Determine whether it is possible to make S equal T, and if it is possible, find the minimum number of operations needed.

Input

The input is given from Standard Input in the following format:
N
S
T

Output

If it is impossible to make S equal T, print -1. If it is possible, print the minimum number of operations needed.

Constraints

• $1 \le N \le 2 \times 10^5$
• S and T are strings of length N consisting of lowercase English letters.

Sample Input 1

4
abab
abba

Sample Output 1

2

You can make S equal T in two operations, as follows.

• Erase the first character of S, and insert that character a at the end of S, making S baba.
• Erase the first character of S, and insert that character b between the 2-nd and 3-rd characters of S, making S abba.

It is impossible to make S equal T in one or fewer operations, so the answer is 2.

Sample Input 2

3
arc
cra

Sample Output 2

2

见题面 Input 部分

见题面 Output 部分