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: Time Limit Exceeded)

import java.util.ArrayList;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String s = sc.next();
		String t = sc.next();

		char[] schar = s.toCharArray();
		char[] tchar = t.toCharArray();

		int sLen = s.length();
		int tLen = t.length();

//		HashMap<Character, ArrayList<Integer>> posMap = new HashMap<Character, ArrayList<Integer>>();
		ArrayList<ArrayList<Integer>> posMap = new ArrayList<ArrayList<Integer>>();
		ArrayList<Integer> poss;
		int idx;
		int zIdx = (int)'z';
		for (idx = 0; idx <= zIdx; idx++) {
			posMap.add(new ArrayList<Integer>());
		}
		for (idx = 0; idx < sLen; idx++) {
			poss = posMap.get(schar[idx]);
			poss.add(idx);
		}

		// 探索
		int curLoops = 0;
		int curPos = -1; // 0文字目に対応できるよう最初だけ-1
		int chPos;
		for (idx = 0; idx < tLen; idx++) {
			poss = posMap.get(tchar[idx]);
			if (poss.size() == 0) {
				// 解なし
				System.out.println("-1");
				return;
			}
			chPos = poss.get(0);
			for (int pos : poss) {
				if (curPos < pos) {
					chPos = pos;
					break;
				}
			}
			if (curPos >= chPos) {
				++curLoops;
			}
			curPos = chPos;
		}

		long answer = ((long) curLoops) * ((long) sLen) + ((long) curPos) + 1L;

		System.out.println(answer);

	}

}