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: Accepted)

import java.util.*;
import static java.lang.Math.*;
import java.math.BigInteger;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		// 入力
		String s = sc.next();
		String t = sc.next();
		
		// 計算
		long result = 0;
		int currentIndex = -1;
		long loop = 0;
		ArrayList<TreeSet<Integer>> alphabet = new ArrayList<TreeSet<Integer>>();
		for(int i = 0; i < 26; i++){
		    TreeSet<Integer> list = new TreeSet<Integer>();
		    alphabet.add(list);
		}
		for(int i = 0; i < s.length(); i++){
	        TreeSet<Integer> list = alphabet.get(s.charAt(i) - 'a');
	        list.add(i);
		}
		//System.out.println(alphabet.toString());
		for(int i = 0; i < t.length(); i++){
		    TreeSet<Integer> list = alphabet.get(t.charAt(i) - 'a');
		    if(list.isEmpty()){
		        result = -1;
		        break;
		    }
		    Integer index = list.higher(currentIndex);
		    if(index == null){
		        loop++;
		        currentIndex = list.first();
		    }else{
		        currentIndex = index;
		    }
		}
		//System.out.println(loop);
		//System.out.println(currentIndex);
		if(result != -1) result = loop * s.length() + currentIndex + 1;
		
		// 出力
		System.out.println(result);
		
	}
}