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
t = gets.chomp
alpha = Hash.new { |h, k| h[k] = [] }
len = s.length
for i in 0..len-1
  alpha[s[i]].push(i)
end

pos = Array.new(len).map{Hash.new}
for i in 0..len-1
  alpha.keys.each do |ch|
    tmp = alpha[ch].bsearch {|x| x > i  }
    if tmp != nil
      pos[i][ch] = tmp - i
    else
      tmp = alpha[ch][0]
      pos[i][ch] = len - i + tmp
    end
  end
end

len2 = t.length
if alpha[t[0]].empty?
  puts -1
  exit
end
ans = alpha[t[0]][0]
now = alpha[t[0]][0]

for i in 1..len2-1
  if alpha[t[i]].empty?
    puts -1
    exit
  end
  ans += pos[now][t[i]]
  now += pos[now][t[i]]
  now -= len if now >= len
end

puts ans + 1