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.Scanner;
 
public class Main {

	public static final MyScanner in = new MyScanner();
	public static int max_repeat = 100;

	public static void main(String[] args) {

		String s = in.next();
		char[] t = in.next().toCharArray();

		int last=0;
		int repeat=0;
		int pow = 0;
		for(int i=0;i<t.length;i++) {
			int idx = s.indexOf(t[i]);
			if (idx==-1) {
				System.out.println(-1);
				return;
			}
			if(last >= idx) {
				repeat+=1;
				if(repeat==10) {
					repeat = 0;
					pow+=1;
					if(pow > 99){
						System.out.println(-1);
						return;
					}
				}
			}
			last = idx;
		}
		System.out.println(s.length()*(repeat+pow*10)+last+1);

	}

	public static class MyScanner{
		Scanner sc = new Scanner(System.in);
		String nextLine() {return sc.nextLine();}
		String next() {return sc.next();}
		int nextInt() {return Integer.valueOf(sc.next());}
	}

}