/**
 * @param {string} n
 * @return {string}
 */

var reverseStr = function(str) {
    var rStr = '';
    for (var i = str.length - 1; i >= 0; i--) {
        rStr = rStr + str[i];
    }
    return rStr;
};
var getDistance = function(a,b) {
    /*var difflength = a.length - b.length;
    difflength = difflength < 0 ? -1*difflength : difflength;
    if (difflength > 0) {
        var zero = '';
        for (var i = 0; i < difflength; i++) {
            zero = zero + '0';
        }
        if (a.length > b.length) {
            b = zero + b;
        } else {
            a = zero + a;
        }
    }
    var str = '';
    for (var i = 0; i < a.length; i++) {
        var dif = parseInt(a[i]) - parseInt(b[i]);
        dif = dif < 0 ? -1*dif : dif;
        str = str + dif;
    }*/
    return parseInt(a) > parseInt(b) ? a - b : b - a;
};
var getPalin = function(firstHalf) {
    reverseHalf = reverseStr(firstHalf);
    return firstHalf + reverseHalf;
}
var updateSolution = function(distance, palin, solution) {
    if (distance < solution.min_dis) {
        solution.palin = palin;
        solution.min_dis = distance;
    } else if (distance === solution.min_dis && parseInt(palin) < parseInt(solution.palin)) {
        solution.palin = palin;
    }
}
var updateOdd = function(firstHalf, solution, n) {
    var reverseHalf = reverseStr(firstHalf);

    for (var i = 0; i < 10; i++) {
        var palin = firstHalf + i + reverseHalf;
        if (palin !== n) {
            updateSolution(getDistance(palin, n), palin, solution);
        }
    }
}
var nearestPalindromic = function(n) {
    var solution = {};
    solution.min_dis = Math.pow(10,18);
    solution.palin = '';
    var firstHalf;
    var palin;

    if (parseInt(n) <= 10) {
        return (n - 1).toString();
    }

    if (n.length % 2 === 0) {
        half = n.length/2;
        firstHalf = n.slice(0, half);
        palin = getPalin(firstHalf);
        if (palin !== n) {
            updateSolution(getDistance(palin, n), palin, solution);
        }

        // plus 1
        firstHalf = (parseInt(n.slice(0, half)) + 1).toString();

        if (firstHalf.length !== half) { // 0
            // go with odd number
            updateOdd(firstHalf.slice(0, firstHalf.length - 1), solution, n);
        } else {
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        }

        // minus 1
        firstHalf = (parseInt(n.slice(0, half)) - 1).toString();
        if (firstHalf === '0') {
            updateSolution(getDistance('9', n), '9', solution);
        }
        if (firstHalf.length !== half) { // 0
            // go with odd number
            updateOdd(firstHalf, solution, n);
        } else {
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        }
    } else {
        half = (n.length - 1)/2;
        firstHalf = n.slice(0, half);
        updateOdd(firstHalf, solution, n);

        if (firstHalf[firstHalf.length - 1] === '0') { // go with even
            firstHalf = (parseInt(n.slice(0, half + 1)) - 1).toString();
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        }

        // plus 1
        firstHalf = (parseInt(n.slice(0, half)) + 1).toString();
        if (firstHalf.length !== half) { // 0
            // go with even number
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        } else {
            updateOdd(firstHalf, solution, n);
        }
        // minus 1
        firstHalf = (parseInt(n.slice(0, half)) - 1).toString();
        if (firstHalf[firstHalf.length - 1] === '0') { // go with even
            firstHalf = (parseInt(n.slice(0, half + 1)) - 1).toString();
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        }

        if (firstHalf.length !== half) { // 0
            // go with even number
            palin = getPalin(firstHalf);
            updateSolution(getDistance(palin, n), palin, solution);
        } else {
            updateOdd(firstHalf, solution, n);
        }
    }


    return solution.palin;
};