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: Runtime Error)


# import sys
# input = sys.stdin.readline
import bisect


def ch_to_int(c):
    return ord(c) - 96


def main():
    s = input()
    t = input()
    pos = 0
    count = 0
    ch = [[] for i in range(26)]

    for i in range(len(s)):
        ch[ch_to_int(s[i])].append(i)

    for i in range(len(t)):
        c = ch_to_int(t[i])
        li = ch[c]

        if len(li) == 0:
            pos = -2
            count = 0
            break

        next_index = bisect.bisect_right(li, pos)
        if next_index >= len(li):
            next_pos = li[0]
            count += 1
            pos = next_pos
        else:
            pos = li[next_index]

    print((pos + 1) + count * len(s))


if __name__ == '__main__':
    main()