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 C# (Mono-csc 3.5.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
class Test
{
    public static void Main()
    {

        string s = Console.ReadLine();
        string t = Console.ReadLine();
        Dictionary<char, int> dic = new Dictionary<char, int>();
        for (int ii = 0; ii < s.Length; ii++)
        {
            if (!dic.ContainsKey(s[ii]))
            {
                dic.Add(s[ii], ii + 1);
            }
            else
            {
                //dic[s[ii]] = ii + 1;
            }
        }
        int ans = -1;
        int sL = s.Length;
        int prvVal = -1;
        for (int i = 0; i < t.Length; i++)
        {
            if (dic.ContainsKey(t[i]))
            {
                var inde = dic[t[i]];
                while (inde <= prvVal)
                {
                    inde = inde + sL;
                }
                prvVal = inde;
                ans = inde;
            }
        }

        Console.Write(ans);
    }

}