function solve(arr) {
    let n = arr.shift();

    let digitsArr = new Array(10).fill(0);
    let countsArr = new Array(16).fill(0);

    for (let i = 0; i < n.length; i++) {
        let digit = Number(n[i]);
        digitsArr[digit]++;
    }

    for (let i = 0; i < digitsArr.length; i++) {
        let count = digitsArr[i];
        if(count > 0){
            countsArr[count]++;
        }
    }

    let differentOddCounts = countsArr.reduce((a, countOfDigitsWithThisOccurence, occurenceOfDigit) => {
        //count different digits that occur odd number of times in string 
        if (occurenceOfDigit % 2 == 1) {
            a += countOfDigitsWithThisOccurence;
        }
        return a;
    }, 0)

    if (differentOddCounts > 1) {
        console.log('No palindromic number available.');
    } else {
        let res = '';
        let oddCountIndex = undefined;
        for (let i = 9; i >= 0; i--) {
            let count = digitsArr[i];
            if(count % 2 == 0) {
                res += i.toString().repeat(count / 2);
            } else {
                oddCountIndex = i;
            }
        }

        let resReversed = res.split('').reverse().join('');
        if(oddCountIndex != undefined){
            let oddCount = digitsArr[oddCountIndex];
            res += oddCountIndex.toString().repeat(oddCount);
        }

        res += resReversed;
        console.log(res);
    }
}