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.*;

public class Main {

    void run() {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String t = sc.next();
        boolean isOK = true;

        List<Integer>[] sArr = new List[26];

        for (int i = 0 ; i  < 26; i++) {
            sArr[i] = new ArrayList<>();
        }

        for (int i = 0; i < s.length(); i++) {
            sArr[s.charAt(i) - 'a'].add(i);
        }

        long ans = 0;
        int currentIdx = 0;
        for (int i = 0; i < t.length(); i++) {
            char c = t.charAt(i);
            if (sArr[c - 'a'].isEmpty()) {
                debug(i, c);
                isOK = false;
                break;
            }

            boolean canFind = false;
            for (int idx : sArr[c - 'a']) {
                if (currentIdx < idx) {
                    currentIdx = idx;
                    canFind = true;
                    break;
                } else {
                    continue;
                }
            }

            if (!canFind) {
                currentIdx = sArr[c - 'a'].get(0);
                ans += s.length();
            }
        }


        System.out.println(isOK ? ans + currentIdx + 1: -1);
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
}