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 PHP7 (7.0.15) (judge verdict: Time Limit Exceeded)

<?php

fscanf(STDIN, "%s", $text);
fscanf(STDIN, "%s", $search);

$text_array = str_split($text);
//foreach(range("a", "z") as $letter){
//    $s_array[$letter]=[];
//}

foreach($text_array as $num => $letter){
    $s_array[$letter][] = $num;
}

foreach(range("a", "z") as $letter){
    if(empty($s_array[$letter])){
        $last_array[$letter] = -1;
    }else {
        $last_array[$letter] = array_last($s_array[$letter]);
    }
}

$search_array = str_split($search);
$offset = 0;
$loop = 0;
foreach($search_array as $letter){
    if($last_array[$letter] == -1){
        echo "-1";
        exit;
    }elseif($last_array[$letter] < $offset){
        $loop++;
        $offset = 0;
    }
    $offset = binarySearch($s_array[$letter], $offset) + 1;
}

echo strlen($text)* $loop + $offset;



function binarySearch($array, $target) {

    $numsLength = count($array);
    $pivot = intdiv($numsLength, 2);
    if ($array[$pivot] >= $target) {
        if($pivot == 0 || $array[$pivot - 1] < $target){
            return($array[$pivot]);
        }
        return(binarySearch(array_slice($array, 0, $pivot), $target));
    }elseif ($array[$pivot] < $target) {
        return(binarySearch(array_slice($array, $pivot), $target));
    }
}
function array_last(array $array)
{
    return end($array);
}