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("")

indexes = {
  'a' => [],
  'b' => [],
  'c' => [],
  'd' => [],
  'e' => [],
  'f' => [],
  'g' => [],
  'h' => [],
  'i' => [],
  'j' => [],
  'k' => [],
  'l' => [],
  'm' => [],
  'n' => [],
  'o' => [],
  'p' => [],
  'q' => [],
  'r' => [],
  's' => [],
  't' => [],
  'u' => [],
  'v' => [],
  'w' => [],
  'x' => [],
  'y' => [],
  'z' => []
}

S.each_with_index do |char, index|
  indexes[char].push(index)
end

pos = -1
loop_count = 0
T.each do |char|
  index = indexes[char].bsearch{ |i| i > pos }
  if index.nil?
    loop_count += 1
    index = indexes[char].first
    if index.nil?
      puts '-1'
      exit
    end
  end

  pos = index
end

puts loop_count * S.count + pos + 1