var assert = require('assert');

const A = [2,3,9,2,5,1,3,7,10]
const B = [2,1,3,4,3,10,6,6,1,7,10,10,10]
const C = [2,9,2,5,7,10]

const isPrime = n => ![...Array(n).keys()].slice(2).map(i => !(n%i)).includes(true) && ![0,1].includes(n)

const excludedValues = B.filter((x, i, array) => {
    const isUnique = array.indexOf(x) === i
    if (!isUnique) return false

    const count = array.filter(y => y === x).length
    return isPrime(count)
});

const result = A.filter(x => !excludedValues.includes(x))

//OK
assert.deepEqual(C, result)