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: Accepted)

fun <T> List<T>.upperBound(element: T): Int where T : Comparable<T> {
    return this
        .binarySearch { if (it > element) 1 else -1 }
        .let { -(it + 1) }
}

fun main(args: Array<String>) {
    val s = readLine()!!
    val t = readLine()!!

    val table = Array(26) { mutableListOf<Int>() }
    for ((i, c) in s.withIndex()) {
        table[c - 'a'].add(i + 1)
    }

    var cur = 0L
    for (c in t) {
        val i = c - 'a'
        if (table[i].isEmpty()) {
            cur = -1
            break
        }

        val p1 = (cur % s.length).toInt()
        val p2 = table[i].upperBound(p1)
        cur += if (p2 < table[i].size) {
            table[i][p2] - p1
        } else {
            s.length - p1 + table[i][0]
        }
    }
    println(cur)
}