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: Time Limit Exceeded)

import bisect

s=input()
t=input()

#print(index)
condition=0
t2=list(set(t))
#print(t2)

for i in range(len(t2)):
 if s.count(t2[i])==0:
   condition=1
   break

if condition==1:
  print(-1)
else:
  index=list()
  for a in range(len(t)):
   index.append([i for i, x in enumerate(s) if x == t[a]])
  
  #print(index)
  b=index[0][0]
  j=1
  loop=0
  count=0
  if len(t)==1:
    print(b+1)
  else:
   while j <= len(t)-1:
     c=bisect.bisect_left(index[j],b)
     #print(j,index[j],b,c,loop)
     if c < len(index[j]) and c != index[j][len(index[j])-1]:
        b=index[j][c]
        #print(j,b,loop)
        j=j+1
        if j==len(t):
          print(b+loop+1)
          break
     else:
        loop=loop+len(s)
        b=index[j][0]
        j=j+1
        if j==len(t):
          print(b+loop+1)
          break
        if loop == len(s)*(10**100):
           print(-1)
           break