1176C · Lose it!

Problem: You are given an array $a$ consisting of $n$ integers. Each $a_i$ is one of the six following numbers: $4, 8, 15, 16, 23, 42$.

Your task is to remove the minimum number of elements to make this array good.

An array of length $k$ is called good if $k$ is divisible by $6$ and it is possible to split it into $\frac{k}{6}$ subsequences $4, 8, 15, 16, 23, 42$.

Examples of good arrays:

• $[4, 8, 15, 16, 23, 42]$ (the whole array is a required sequence);
• $[4, 8, 4, 15, 16, 8, 23, 15, 16, 42, 23, 42]$ (the first sequence is formed from first, second, fourth, fifth, seventh and tenth elements and the second one is formed from remaining elements);
• $[]$ (the empty array is good).

Examples of bad arrays:

• $[4, 8, 15, 16, 42, 23]$ (the order of elements should be exactly $4, 8, 15, 16, 23, 42$);
• $[4, 8, 15, 16, 23, 42, 4]$ (the length of the array is not divisible by $6$);
• $[4, 8, 15, 16, 23, 42, 4, 8, 15, 16, 23, 23]$ (the first sequence can be formed from first six elements but the remaining array cannot form the required sequence).

Input Format: The first line of the input contains one integer $n$ ($1 \le n \le 5 \cdot 10^5$) — the number of elements in $a$.

The second line of the input contains $n$ integers $a_1, a_2, \dots, a_n$ (each $a_i$ is one of the following numbers: $4, 8, 15, 16, 23, 42$), where $a_i$ is the $i$-th element of $a$.

Output Format: Print one integer — the minimum number of elements you have to remove to obtain a good array.