rage-quit

function solve(arr) {
    text = arr[0].replace(/[a-z]/ig, (m) => m.toUpperCase());

    const uniqueChars = new Set(text.match(/[^\d]/g));

    console.log(`Unique symbols used: ${uniqueChars.size}`);

    let result = [];

    for (const e of [...text.matchAll(/(?<chrs>[^\d]+)(?<n>\d+)/g)]) {
        const {chrs, n} = e.groups;
        result.push(chrs.repeat(Number(n)));
    }
    console.log(result.join(''));
}