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 Haskell (GHC 8.8.3) (judge verdict: Time Limit Exceeded)

import Data.Char
import Data.List
import qualified Data.IntMap.Strict as M

main = do
    ss <- zipWith (\i c -> (ord c - ord 'a', i)) [1..] <$> getLine
    ts <- map (\c -> ord c - ord 'a') <$> getLine
    let abc = foldr (\(c,i) m -> M.insertWith (++) c [i] m) M.empty ss
    let f Nothing _ = Nothing
        f (Just (k,i)) c = case idx of
                            Just j -> if j > i then (Just (k,j)) else (Just (k+1,j))                       
                            _ -> Nothing
                where idx = M.lookup c abc >>= \ks -> safehead ((dropWhile (<= i) ks) ++ ks)
                      safehead ks = if null ks then Nothing else Just (head ks)
    let ans = case (foldl' f (Just (0,0)) ts) of
                Nothing -> -1
                Just (k,i) -> (length ss) * k + i
    print ans