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: Accepted)

s=gets.chomp.split("")
t=gets.chomp.split("")

idx=Hash.new { |h, k| h[k] = [] }

s=s+s
s.each_with_index do |c,i|
  idx[c] << i
end
l = []
t.each do |c|
  if idx[c].size == 0
    puts -1
    exit
  end

  if l.size == 0
    prev = -1
  else
    prev = l[-1]
  end
  
  tmp = idx[c].bsearch {|x| x >  prev}
  if tmp == nil
    l << idx[c][0]
  else
    l << tmp
  end
end

prev=Float::INFINITY
cnt = 0
l.each do |v|
  if prev > v
    cnt += 1
  end
  prev = v
end
puts s.size * (cnt-1) + l[-1] + 1