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 (3.8.2) (judge verdict: Time Limit Exceeded)

s = input()
t = input()
l_s = len(s)
l_t = len(t)

s2 = s + s
l_s2 = len(s2)

next_idx_1 = [[l_s2] * 26 for i in range(l_s2+1)]

for i in reversed(range(l_s2)):
    for j in range(26):
        next_idx_1[i][j] = next_idx_1[i+1][j]
    next_idx_1[i][ord(s2[i]) - ord("a")] = i

next_idx_2 = [[l_s2] * 26 for i in range(l_s2)]

for i in reversed(range(1, l_s2)):
    for j in range(26):
        next_idx_2[i-1][j] = next_idx_2[i][j]
    next_idx_2[i-1][ord(s2[i]) - ord("a")] = i

cur_idx = 0
for i in range(l_t):
    if i == 0:
        idx = next_idx_1[cur_idx%l_s][ord(t[i]) - ord("a")]

    else:
        idx = next_idx_2[cur_idx%l_s][ord(t[i]) - ord("a")]

    if idx == l_s2:
        print("-1")
        exit()

    cur_idx += idx - (cur_idx % l_s)
    
print(cur_idx+1)