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.



Sample input:
contest
son


Sample output:
10

Submission status: Wrong Answer

Solution code:
import bisect

s = list(input())
t = list(input())

if not set(t).issubset(set(s)):
    print(-1)
    exit()

indices = [[] for _ in range(26)]
idx = [0]*26

for i in range(len(s)):
    indices[ord(s[i]) - 97].append(i)

now = 0
rep = 1
for i in range(len(t)):
    x = ord(t[i]) - 97
    y = bisect.bisect_left(indices[x], now)
    if y == len(indices[x]) or now > indices[x][y]:
        rep += 1
        now = indices[x][0]
    else:
        now = indices[x][y]

print(len(s)*(rep-1) + now + 1)