Taco's Minimum Swaps Challenge

You are given two strings s and t of equal length. Your task is to determine the minimum number of swap operations required to transform s into t. In one swap operation, you can choose two positions in s (they can be the same or different) and swap the characters at those positions.

The transformation is only possible if s and t have the same overall frequency of each character. If they do not, output -1.

Note:

• The input strings consist of lowercase letters only.
• The length of the strings satisfies \(1 \leq |s| = |t| \leq 10^6\).
• Each swap operation can potentially fix two mismatched positions.

Example:

Input:
abcd
cdab
Output:
2

</p>

inputFormat

The input is given via stdin and consists of two lines:

1. The first line contains the string s.
2. The second line contains the string t.

outputFormat

Output a single integer — the minimum number of swap operations required to transform s into t. If it is impossible to do so, output -1.

The output should be written to stdout.

## sample

abcd
cdab

2