/**
 * file: dpLcsMaximizer.kt
 * author: San Skulrattanakulchai
 * date: 2018-11-02
 * 
 * This program differs from `dpLcs.kt` in that it uses both the
 * dp table `opt` and the maximizer table `maxer`.
 */

fun main(args: Array<String>) {
    val x = readLine()!!
    val y = readLine()!!

    fun String.explode() = this.toList().joinToString(separator=" ")

    println("""
        |x: ${x.explode()}
        |y: ${y.explode()}
        |LCS(x, y): ${dpLcs(x, y).explode()}
        """.trimMargin())
}

enum class Dir { NONE, RIGHT, DOWN, DIAG }

fun dpLcs(x: String, y: String): String {
    val m = x.length
    val n = y.length

    val opt = Array<IntArray>(m+1) { IntArray(n+1) }
    val maxer = Array<Array<Dir>>(m) { Array<Dir>(n) { Dir.NONE } }

    fun fillTable() {
        for (i in m-1 downTo 0) {
            for (j in n-1 downTo 0) {
                if (x[i] == y[j]) {
                    opt[i][j] = opt[i+1][j+1] + 1
                    maxer[i][j] = Dir.DIAG
                } else if (opt[i+1][j] > opt[i][j+1]) {
                    opt[i][j] = opt[i+1][j]
                    maxer[i][j] = Dir.DOWN
                } else {
                    opt[i][j] = opt[i][j+1]
                    maxer[i][j] = Dir.RIGHT
                }
            }
        }
    }

    fun lcs(): String {
        val sb = StringBuilder()
        var i = 0
        var j = 0
        while ((i < m) && (j < n)) {
            when (maxer[i][j]) {
                Dir.DIAG -> {
                    sb.append(x[i])
                    i++
                    j++
                }
                Dir.DOWN -> i++
                Dir.RIGHT -> j++
                else -> throw Exception("Incorrect maximizer value.")
            }
        }
        return sb.toString()
    }

    fillTable()
    return(lcs())
}