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 (3.8.2) (judge verdict: Wrong Answer)

import bisect
s = str(input())
t = str(input())

alpha2num = lambda c: ord(c) - ord('a')

S2 = [[] for i in range(26)]
for i in range(len(s)):
  S2[alpha2num(s[i])].append(i)
  
#print(S2)
time = 0
place = 0
for i in range(len(t)):
  now = alpha2num(t[i])
  if S2[now] == []:
    print(-1)
    quit()
  else:
    index = bisect.bisect_left(S2[now], place)
    if index == len(S2[now]):
      place = S2[now][0]
      time += 1
    else:  
      place = S2[now][index]
  #print(place, time)  
    
    
ans = len(s) * time + place + 1
print(ans)