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 Ruby (2.3.3) (judge verdict: Time Limit Exceeded)

s = gets.chomp
s_len = s.length
t = gets.chomp

s_array = s.split('')
t_array = t.split('')

check = t_array.select {|c| !s_array.include?(c) }

if check.empty?
    s2 = s * 2
    t_uniq_array = t_array.uniq
    indexes = {}
    t_uniq_array.each do |t_e|
        r = s.split('').map.with_index { |e,i| e == t_e ? i : nil }.compact
        r.push(r.first + s_len)
        indexes[t_e] = r
    end
    ans = 0

    memo = {}
    t_uniq_array.each {|t_e| memo[t_e] = {} }

    t_array.each do |t_e|
        start = ans % s_len
        a = memo[t_e][start]
        if a == nil
            a = indexes[t_e].bsearch{|i| start <= i }
            memo[t_e][start] = a
        end
        ans += (a - start + 1)
    end
    print ans
else
    puts "-1"
end