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: Wrong Answer)

import sys
input = sys.stdin.readline

s = input().rstrip()
t = input().rstrip()
n = len(s)
m = len(t)

import heapq

dic = {}
for i in range(ord("a"), ord("z") + 1):
    dic[chr(i)] = []

# print(dic)

for i in range(n):
    heapq.heappush(dic[s[i]], i + 1)

# print(dic)
keys = set(dic.keys())
ans = 0

for i in t:
    if len(dic[i]) == 0:
        print(-1)
        sys.exit()
    idx = heapq.heappop(dic[i])
    if ans >= idx:
        idx += ((ans - idx) // n) * n
        if idx <= ans:
            idx += n
        ans = idx
        heapq.heappush(dic[i], idx)
    else:
        ans = idx
        if len(dic[i]) > 0:
            if dic[i][-1] >= idx:
                idx += ((dic[i][-1] - idx) // n) * n
                if idx <= dic[i][-1]:
                    idx += n
        heapq.heappush(dic[i], idx + n)
    # print(ans)

print(ans)