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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict"

const arg_str = require('fs').readFileSync('/dev/stdin', 'UTF-8')
const args_lines = arg_str.split('\n')
const s = args_lines[0]
const t = args_lines[1]

const t_array = t.split('')

let pos_array = []

t_array.forEach(item=>{
    const pos = s.indexOf(item) + 1
    pos_array.push(pos)
})

const is_eval = pos_array.filter(x=>x==0).length > 0

if(is_eval){
  console.log(-1)
  return
}

let total = 0
pos_array.forEach((item, index)=>{
    if(index == 0){
        total = pos_array[index]
        return
    }
    if(pos_array[index - 1] < pos_array[index]){
        total += pos_array[index] - pos_array[index - 1]
    }else{
        total += s.length - pos_array[index - 1] + pos_array[index]
    }
})

console.log(total)