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 PyPy2 (5.6.0) (judge verdict: Wrong Answer)

import collections
s = raw_input()
t = raw_input()
sb = s + s
h = {chr(ord('a') + i):-1 for i in range(26)}
dp = []
for j in range(len(sb)-1,-1,-1):
	h[sb[j]] = j
	dp.append({k:h[k] for k in h})
dp = dp[::-1]
i = 0
j = 0
c = 0
while(j < len(t)):
	ha = dp[i]
	letter = t[j]
	if ha[letter] != -1:
		i = ha[letter]
		j += 1
	else:
		j = -1
		break

	if i >= len(s):
		i %= len(s)
		c+=1
		
print (c * len(s) + i + 1) if j != -1 else -1