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 PyPy3 (2.4.0) (judge verdict: Time Limit Exceeded)

s = str(input())
t= str(input())

sdict = {}
for i in range(len(s)):
    if s[i] not in sdict:
        sdict[s[i]]=[]
    sdict[s[i]].append(i+1)
    
#print(sdict)

#二分木探索
def search(list_,mark_,sta,gol):
    if  sta == gol:
            return list_[sta]
    else:
            mid = (gol+sta)//2
            if list_[mid]>mark_:
                return search(list_,mark_,sta,mid)
            else:
                return search(list_,mark_,mid+1,gol)

ans = 0
mark = 0
for _ in range(len(t)):
    target = t[_]
    if target not in sdict:
        ans = -1
        break
    else:
        if sdict[target][-1]<=mark:
            mark = sdict[target][0]
            ans += len(s)
        elif sdict[target][0]>mark:
            mark = sdict[target][0]
        else:
            posi = search(sdict[target],mark,0,len(sdict[target])-1)
            mark = posi
        
if ans != -1:
    ans += mark
print(ans)