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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Arrays;
import java.util.OptionalInt;
import java.util.Scanner;
import java.util.stream.IntStream;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String m = sc.nextLine().trim();
        String c = sc.nextLine().trim();

        if (c.chars().anyMatch(i -> m.indexOf(i) == -1)) {
            System.out.println(-1);
            return;
        }

        long index = 0;
        for (char ch : c.toCharArray()) {
            OptionalInt first;

            final long var = index % m.length();
            first = allIndex(m, ch).filter(i -> i > var).findFirst();


            if (first.isPresent()) {
                index = (index / m.length()) * (m.length()) + first.getAsInt();
                continue;
            }

            index = ((index / m.length()) + 1) * (m.length()) + allIndex(m, ch).findFirst().orElseThrow(IndexOutOfBoundsException::new);
        }
        System.out.println(index + 1);
    }

    private static IntStream allIndex(String m, int c) {
        return IntStream.iterate(m.indexOf(c), i -> m.indexOf(c, i + 1)).filter(i -> i > -1).limit(m.length());
    }
}