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 Python (3.4.3) (judge verdict: Accepted)

import sys
import numpy as np
import bisect
s = input()
t = input()



count = 0
s_len = len(s)
s_list = np.zeros(len(s))
t_list = []*len(t)
indexes = []

for i in range(26):
  
  indexes.append([j for j, x in enumerate(s) if x == chr(i + ord('a')) ])
  


for i,k in enumerate(t):

  index = indexes[ord(k)-ord('a')]
  
  if len(index) == 0:
    print(-1)
    sys.exit(0)
  else:
    t_list.insert(i,index)
    


pre = -1
for i in range(len(t)):
  
  #high = [j  for j in t_list[i] if j > pre]
  high = bisect.bisect_left(t_list[i], pre+1) 

  if high >= len(t_list[i]):
    
    count += s_len - pre  + t_list[i][0]
    pre = t_list[i][0] 
  else:
    
    count += t_list[i][high] - pre 
    pre = t_list[i][high]

print(count)