Problem:
Score : 400 points

Problem Statement

Mr. Takahashi has a string s consisting of lowercase English letters.
He repeats the following operation on s exactly K times.

Choose an arbitrary letter on s and change that letter to the next alphabet. Note that the next letter of z is a.

For example, if you perform an operation for the second letter on aaz, aaz becomes abz.
If you then perform an operation for the third letter on abz, abz becomes aba.

Mr. Takahashi wants to have the lexicographically smallest string after performing exactly K operations on s.
Find the such string.

Constraints

1≤|s|≤10^5

All letters in s are lowercase English letters.

1≤K≤10^9

Input

The input is given from Standard Input in the following format:

s
K

Output

Print the lexicographically smallest string after performing exactly K operations on s.

Sample Input 1

xyz
4

Sample Output 1

aya

For example, you can perform the following operations: xyz, yyz, zyz, ayz, aya.

Sample Input 2

a
25

Sample Output 2

z

You have to perform exactly K operations.

Sample Input 3

codefestival
100

Sample Output 3

aaaafeaaivap

Solution in Kotlin (1.0.0) (judge verdict: Accepted)

@file:Suppress("DuplicatedCode")

import java.io.IOException
import java.io.InputStream
import java.io.PrintWriter
import java.util.NoSuchElementException

fun main(args: Array<String>) {
    PrintWriter(System.out).use { out ->
        C.solve(C.FastScanner(), out)
        out.flush()
    }
}

private fun C.solve(sc: C.FastScanner, out: PrintWriter) {
    val s = sc.next().toCharArray()
    var k = sc.nextInt()
    for (i in s.indices) {
        if (s[i] == 'a') continue
        val diff = 'z' + 1 - s[i]
        if (diff < k) {
            s[i] = 'a'
            k -= diff
        } else if (diff == k) {
            s[i] = 'a'
            k = 0
            break
        }
    }

    if (k != 0) {
        s[s.size - 1] = s[s.size - 1] + (k % 26)
    }

    println(String(s))
}

@Suppress("MemberVisibilityCanBePrivate")
private object C {
    private const val zeroCode = '0'.toInt()
    private const val nineCode = '9'.toInt()

    class FastScanner {
        private val `in`: InputStream = System.`in`
        private val buffer = ByteArray(2048)
        private var ptr = 0
        private var buflen = 0

        private fun hasNextByte(): Boolean {
            if (ptr < buflen) {
                return true
            } else {
                ptr = 0
                try {
                    buflen = `in`.read(buffer)
                } catch (e: IOException) {
                    e.printStackTrace()
                }
                if (buflen <= 0) {
                    return false
                }
            }
            return true
        }

        private fun readByte(): Byte = if (hasNextByte()) buffer[ptr++] else -1

        private fun readByteAsInt(): Int = if (hasNextByte()) buffer[ptr++].toInt() else -1

        operator fun hasNext(): Boolean {
            while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++
            return hasNextByte()
        }

        operator fun next(): String {
            if (!hasNext()) throw NoSuchElementException()

            return buildString {
                var b = readByteAsInt()

                while (isPrintableChar(b)) {
                    appendCodePoint(b)
                    b = readByteAsInt()
                }
            }
        }

        fun toCharIterator(): CharIterator = object : CharIterator() {
            private var nextByte: Byte = readByte()

            override fun hasNext(): Boolean = isPrintableChar(nextByte)

            override fun nextChar(): Char {
                val res = nextByte
                nextByte = readByte()
                return res.toChar()
            }

        }

        fun nextLong(): Long {
            if (!hasNext()) throw NoSuchElementException()
            var n: Long = 0
            var minus = false
            var b = readByteAsInt()

            if (b == '-'.toInt()) {
                minus = true
                b = readByteAsInt()
            }

            if (b !in zeroCode..nineCode) {
                throw NumberFormatException()
            }

            while (true) {
                if (b in zeroCode..nineCode) {
                    n *= 10
                    n += b - zeroCode.toLong()
                } else if (b == -1 || !isPrintableChar(b)) {
                    return if (minus) -n else n
                } else {
                    throw NumberFormatException()
                }

                b = readByteAsInt()
            }
        }

        fun nextInt(): Int {
            val nl = nextLong()
            if (nl < Int.MIN_VALUE || nl > Int.MAX_VALUE) throw NumberFormatException()
            return nl.toInt()
        }

        fun nextDouble(): Double {
            return next().toDouble()
        }

        fun readIntArray(n: Int): IntArray {
            val arr = IntArray(n)

            for (i in 0 until n) {
                arr[i] = nextInt()
            }

            return arr
        }

        fun readBigInt(capacity: Int): IntArray {
            if (!hasNext()) throw NoSuchElementException()

            val arr = IntArray(capacity)
            var len = 0
            arr[0] = readByteAsInt() - zeroCode
            while (arr[len] in 0..9) {
                len++
                arr[len] = readByteAsInt() - zeroCode
            }

            return arr.sliceArray(0 until len)
        }

        companion object {
            private inline fun isPrintableChar(c: Int): Boolean {
                return c in 33..126
            }

            private inline fun isPrintableChar(c: Byte): Boolean {
                return c in 33..126
            }
        }
    }
}