
Score : 500 points
Problem StatementGiven 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.
InputInput is given from Standard Input in the following format:
s
t
OutputIf there exists an integer i satisfying the following condition, print the minimum such i; otherwise, print -1.
Sample Input 1contest
son
Sample Output 110
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 2contest
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 3contest
sentence
Sample Output 333
Note that the answer may not fit into a 32-bit integer type, though we cannot put such a case here.
