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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.util.*

fun main(args: Array<String>) {
    val s = readLine()!!
    val t = readLine()!!
    val map = HashMap<Char, ArrayList<Long>>()
    s.toCharArray().forEachIndexed { index, c ->
        val i = index.toLong()
        if (map[c] == null) {
            map[c] = arrayListOf(i + 1)
        } else {
            map[c]!!.add(i + 1)
        }
    }
    map.values.forEach { it.sort() }
    //map.values.forEach { println(it.joinToString(" ")) }

    var prevIndex = 0L
    var ans = 0L
    val length = s.length.toLong()
    t.toCharArray().forEach { c ->
        if (map[c] == null) {
            println("-1")
            return
        }
        val list = map[c]!!
        var returnIndex = list.binarySearch(prevIndex)
        if (returnIndex < 0) returnIndex = returnIndex.inv()
        if (returnIndex >= list.size) {
            var frontIndex = list.binarySearch(0L)
            if(frontIndex < 0) frontIndex = frontIndex.inv()
            ans += list[frontIndex] + length - prevIndex
            //println("if: ${list[frontIndex] + s.length - prevIndex}")
            prevIndex = list[frontIndex]
        } else {
            ans += list[returnIndex] - prevIndex
            //println("else: ${list[returnIndex] - prevIndex}")
            prevIndex = list[returnIndex]
        }
    }
    println(ans)
}