The one of the edition distance (II)

At this stage, you surely already know that some problems are so classic that blah, blah, blah. Nothing new with this problem. Now, we ask you to compute the minimum cost to insert letters into or to modify letters from two words $w_1$ and $w_2$ to make them identical. Both words are made up of only letters chosen among the $n$ smallest lowercase letters (for instance, for $n=4$ , the alphabet is $\{a, b, c, d\}$ ). For every letter (call it $x$ ), inserting an $x$ in any place in any word has cost $I_x$ . The cost to transform a letter $x$ into a letter $y$ is given by $\lceil(I_x+I_y)/4\rceil$ , i.e., a fourth part, ceiling, of the sum fo the insertion costs $I_x$ and $I_y$ .

Input

Input consists of several cases. Each case begins with $2\leq n\leq 26$ , followed by $n$ strictly positive natural numbers $I_{\mbox{\texttt{a}}}, I_{\mbox{\texttt{b}}}, I_{\mbox{\texttt{c}}}, \ldots$. Follow two words $w_1$ and $w_2$ made up of between 1 and 1000 lowercase letters chosen among the $n$ smallest letters. Assume $1\leq I_x\leq 1000$ for every letter $x$ .

Output

For every case, print the minimum cost to make $w_1$ and $w_2$ identical.

Problem information

Author: Unknown
Translator: Carlos Molina

Generation: 2026-01-25T11:25:56.761Z