{"raw_statement":[{"iden":"problem statement","content":"You are given strings $s$ and $t$, both of length $N$. $s$ and $t$ consist of `0` and `1`. Additionally, in these strings, the same character never occurs three or more times in a row.\nYou can modify $s$ by repeatedly performing the following operation:\n\n*   Choose an index $i$ ($1 \\leq i \\leq N$) freely and invert the $i$\\-th character in $s$ (that is, replace `0` with `1`, and `1` with `0`), under the condition that the same character would not occur three or more times in a row in $s$ after the operation.\n\nYour objective is to make $s$ equal to $t$. Find the minimum number of operations required."},{"iden":"constraints","content":"*   $1 \\leq N \\leq 5000$\n*   The lengths of $s$ and $t$ are both $N$.\n*   $s$ and $t$ consists of `0` and `1`.\n*   In $s$ and $t$, the same character never occurs three or more times in a row."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$s$\n$t$"},{"iden":"sample input 1","content":"4\n0011\n0101"},{"iden":"sample output 1","content":"4\n\nOne possible solution is `0011` → `1011` → `1001` → `1101` → `0101`."},{"iden":"sample input 2","content":"1\n0\n0"},{"iden":"sample output 2","content":"0"},{"iden":"sample input 3","content":"8\n00110011\n10101010"},{"iden":"sample output 3","content":"10"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}