find([1, 2, 3, 2, 1, 4]); // [3, 4]

find([5, 6, 7]); // [5, 6, 7]

find([]); // []

find([8, 8, 7, 9, 9]); // [7]

find([10]); // [10]

find([2, 2, 2, 2, 3, 3, 4, 5, 4]); // [5]

function find(arr) {

if (arr.length === 0) return [];

arr.

((a, b) => a - b);

const items = [];

for (let i = 0; i < arr.length; i++) {

const first = i ===

|| arr[i] !== arr[i - 1];

const second =

i === arr.length - 1 || arr[i] !== arr[i + 1];

if (

) {

items.push(arr[i]);

}

}

return items;

}