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)

# coding: utf-8
class LoopString < Array
  def initialize(s)
    self.replace(s.chomp.split(''))
    @place = Hash.new {|h,k| h[k] = [] }
    self.each_with_index do |ch, idx|
      @place[ch] << idx
    end
    @place.default = nil
  end
  def index(ch, p1)
    return -1 unless @place[ch]
    p2 = p1 % self.length
    p3 = @place[ch].bsearch {|p4| p4 >= p2 }
    (p3 == nil) ? (p1 - p2 + self.length + @place[ch][0]) : (p1 - p2 + p3)
  end
  def bubun(t)
    t.chomp.split('').reduce(0) do |pos, ch|
      p2 = self.index(ch, pos)
      return -1 if p2 < 0
      p2 + 1
    end
  end
  def to_s
    @str
  end
end

puts LoopString.new(ARGF.gets).bubun(ARGF.gets)