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: Runtime Error)

import bisect


def next(ch,k):
    global N,dcs
    ch_=k%N
    #print(ch,ch_,k)
    #print(dcs[ch][ch_]+1)
    #print(dcs[ch])
    #print(dcs[ch][ch_]+1)
    #print(N)
    A=bisect.bisect_left(dcs[ch],dcs[ch][max(0,ch_-1)]+1,ch_,2*N-1)
    B = N*((k//N))
    #print(A,B,k//N,k,N)

    return A+B#+A//N


import numpy as np

s=input()
t=input()

td=list(set(t))

N=len(s)
d={}

import sys

R = set(list(s))
L = set(list(t))

if not(L <= R):
    print(-1)
    sys.exit(2)

for std in td:
    d[std] =[]


for i in range(len(s)*2+1):
    #nd[s[i]]

    for std in td:            
        if s[i%N]==std:
            d[std].append(1)
        else:
            d[std].append(0)


dcs={}
for std in td:
    dcs[std]=np.cumsum(d[std])


last=-1
for ts in t:
    #print(last)
    last=next(ts,last+1)


print(last+1)