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.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		char[] s = scan.nextLine().toCharArray();
		char[] t = scan.nextLine().toCharArray();
		Map<Character, List<Integer>> map = new HashMap<>();

		int lastIndex = -1;
		int loopCnt = 0;
		boolean notExists = false;
		List<Integer> tmpL = new ArrayList<>();

		// 最大値を超えるような条件は与えられない
//		double max = Math.pow(10, 100);

		// 文字と要素番号をマップに格納
		for (int i = 0; i < s.length; i++) {
			tmpL = map.get(s[i]);
			if (tmpL == null) {
				tmpL = new ArrayList<>();
				map.put(s[i], tmpL);
			}
			tmpL.add(i);
		}

		// 文字列tの文字を前方から順次比較
		boolean tmpF = false;
		for (char c : t) {
			tmpL = map.get(c);
			if (tmpL == null) {
				notExists = true;
				break;
			}
			for (int i : tmpL) {
				if (i > lastIndex) {
					lastIndex = i;
					tmpF = true;
					break;
				}
			}
			if (!tmpF) {
				loopCnt++;
				lastIndex = tmpL.get(0);
			}
			tmpF = false;
		}
		if (notExists) {
			System.out.println(-1);
		}
		else {
			System.out.println((s.length * loopCnt) + lastIndex + 1);
		}
	}
}