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.io.ByteArrayInputStream;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        main1(sc);
    }

    private static class KP {
    	char a;
    	long index;

    	KP(char a, long index) {
    		this.a = a;
    		this.index = index;
    	}

    	public String toString() {
    		return "{c:" + a + ", i" + index + "}";
    	}
    }

    public static void main1(Scanner sc) {

    	String base = sc.next();
    	String target = sc.next();

    	HashSet<Character> bs = new HashSet<Character>(50);
    	HashSet<Character> cs = new HashSet<Character>(50);

    	for (char c : base.toCharArray()) {
    		cs.add(c);
    	}

    	LinkedList<KP> l = new LinkedList<KP>();
    	int i = 0;
    	for (char c : base.toCharArray()) {
    		bs.add(c);
    		if (cs.contains(c)) {
    			l.add(new KP(c, i));
    		}
    		i++;
    	}

    	for (char c: target.toCharArray()) {
    		if (!bs.contains(c)) {
    			System.out.println("-1");
    			return;
    		}
    	}

    	int cnt = 0;
    	char[] tgt = target.toCharArray();
    	for (int k = 0; k < 100000; k++) {
    		for (KP ent: l) {
    			if (tgt[cnt] == ent.a) {
    				if (cnt < tgt.length -1 ) {
        				cnt++;
    				} else {
    					System.out.println((k) * base.length() + ent.index + 1);
    					return;
    				}
    			}
    		}
    	}

    }

	public static void maina(String[] args) throws Exception {
		String in2 = "contest\r\n" +
				"son";

		String in3 = "contest\r\n" +
				"programming";

		String in = "contest\r\n" +
				"sentence";

		Scanner sc = new Scanner(new ByteArrayInputStream(in.getBytes()));
		main1(sc);
	}
}