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, T = gets.chomp, gets.chomp

I = [nil]*('z'.ord-'a'.ord+1)
IS = [nil]*S.size
S.chars.reverse_each.with_index{|c,i|
	c, i = c.ord-'a'.ord, S.size-1-i
	IS[i], I[c] = I[c], i
}

ICache = [nil]*('z'.ord-'a'.ord+1)
p T.each_char.inject([0,0]){|acc,c|
	id, im, c = *acc, c.ord-'a'.ord
	ic = (ICache[c]&&ICache[c]<=im) ? ICache[c] : I[c]
	break [0,-1] unless ic
	ic = IS[ic] while ic && ic < im
	if ic.nil?
		id += 1
		ic = I[c]
	end
	ICache[c] = ic
	next [id, ic+1]
}.tap{|a,b| break a*S.size+b }