6867: String painter
[Creator : ]
Description
There are two strings $A$ and $B$ with equal length. Both strings are made up of lower case letters. Now you have a powerful string painter. With the help of the painter, you can change a segment of characters of a string to any other character you want. That is, after using the painter, the segment is made up of only one kind of character. Now your task is to change $A$ to $B$ using string painter. What’s the minimum number of operations?
给出字符串 $A$ 和 $B$，每一次我们可以使用一种颜色（用字母代替）刷任意一个连续子序列，问将字符串 $A$ 变成字符串 $B$ 最少需要刷多少次。
给出字符串 $A$ 和 $B$，每一次我们可以使用一种颜色（用字母代替）刷任意一个连续子序列，问将字符串 $A$ 变成字符串 $B$ 最少需要刷多少次。
Input
Input contains multiple cases.
Each case consists of two lines:
The first line contains string $A$.
The second line contains string $B$.
The length of both strings will not be greater than $100$.
Each case consists of two lines:
The first line contains string $A$.
The second line contains string $B$.
The length of both strings will not be greater than $100$.
Output
A single line contains one integer representing the answer.
Sample 1 Input
zzzzzfzzzzz
abcdefedcba
abababababab
cdcdcdcdcdcd
Sample 1 Output
6
7