Problem:
Score : 500 points

Problem Statement

Given are two strings s and t consisting of lowercase English letters. Determine if there exists an integer i satisfying the following condition, and find the minimum such i if it exists.

Let s' be the concatenation of 10^{100} copies of s. t is a subsequence of the string {s'}_1{s'}_2\ldots{s'}_i (the first i characters in s').

Notes

A subsequence of a string a is a string obtained by deleting zero or more characters from a and concatenating the remaining characters without changing the relative order. For example, the subsequences of contest include net, c, and contest.

Constraints

1 \leq |s| \leq 10^5

1 \leq |t| \leq 10^5

s and t consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s
t

Output

If there exists an integer i satisfying the following condition, print the minimum such i; otherwise, print -1.

Sample Input 1

contest
son

Sample Output 1

10

t = son is a subsequence of the string contestcon (the first 10 characters in s' = contestcontestcontest...), so i = 10 satisfies the condition.

On the other hand, t is not a subsequence of the string contestco (the first 9 characters in s'), so i = 9 does not satisfy the condition.

Similarly, any integer less than 9 does not satisfy the condition, either. Thus, the minimum integer i satisfying the condition is 10.

Sample Input 2

contest
programming

Sample Output 2

-1

t = programming is not a substring of s' = contestcontestcontest.... Thus, there is no integer i satisfying the condition.

Sample Input 3

contest
sentence

Sample Output 3

33

Note that the answer may not fit into a 32-bit integer type, though we cannot put such a case here.

Solution in Scala (2.11.7) (judge verdict: Accepted)

import java.io._
import java.util.StringTokenizer
import scala.util.control.Breaks.{breakable,break}
import scala.collection.mutable.{Map, Stack, Queue, PriorityQueue, Set}

object Main extends App {
  val in = new InputReader(System.in)
  val pw = new PrintWriter(System.out)

  val s = in.next()
  val t = in.next()

  val sl = s.length
  val tl = t.length

  //
  val indices = Array.fill[List[Int]](26)(Nil)
  for (i <- 0 until sl) {
    val ind = s(i).toInt - 97
    indices(ind) = i :: indices(ind)
  }

  val hoge: Array[(Array[Int], Int)] = // (indices, length)
    indices.map{ indice =>
      (indice.reverse.toArray, indice.length)
    }


  def check(i: Int, nowi: Int, cnum: Int): Boolean = {
    hoge(cnum)._1(i) > nowi
  }

  // 条件を満たす最小の値を返す
  def binarySearch(min: Int, max: Int, nowi: Int, cnum: Int): Int = {
    val mid: Int = (max + min) / 2
      (max - min) match{
      case 0 | 1 =>
        check(min, nowi, cnum) match{
          case true  => min
          case false => max
        }
      case _ =>
        (check(mid, nowi, cnum)) match{
          case true  => binarySearch(min, mid, nowi, cnum)
          case false => binarySearch(mid, max, nowi, cnum)
        }
    }
  }


  var ans = 0L
  var nowi = -1
  breakable {
    for (c <- t) {
      val cnum = c.toInt-97
      val (indice, len) = hoge(cnum)
      if (len == 0) {
        ans = -1
        break
      }
      else {
        if (nowi >= indice(len-1)) {
          ans += sl
          nowi = indice(0)
        }
        else {
          val ind = binarySearch(0, len-1, nowi, cnum)
          nowi = indice(ind)
        }
      }
    }

    ans += nowi + 1
  }

  println(ans)
}

object Sub {
  def print2DimArray[A](mat: Array[Array[A]]): Unit = {
    mat.foreach(lin => println(lin.deep))
  }
}

class InputReader(stream: InputStream) {
  private[this] val reader = new BufferedReader(new InputStreamReader(stream))
  private[this] var tokenizer: StringTokenizer = new StringTokenizer(reader.readLine())
  def next(): String = {
    while (!tokenizer.hasMoreTokens()) {
      tokenizer = new StringTokenizer(reader.readLine())
    }
    tokenizer.nextToken()
  }
}