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 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Text;
using System.Numerics;
using System.IO;


namespace SolutionCS
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            string t = Console.ReadLine();

            int[,] l = new int[s.Length, 26];
            int[] count = new int[26];
            for (int j = 0; j < 26; j++)
            {
                count[j] = -1;
                for (int i = 0; i < s.Length; i++)
                {
                    l[i, j] = -1;
                }
            }

            string ss = s + s;
            for (int i = ss.Length - 1; i > 0; i--)
            {
                int charInd = ss[i] - 'a';
                count[charInd] = 1;


                int arrInd = (i-1) % s.Length;

                for (int j = 0; j < 26; j++)
                {
                    if(l[arrInd, j] < 0)
                    {
                        l[arrInd, j] = count[j];
                    }

                    if (count[j] >= 0)
                    {
                        count[j]++;
                    }
                }
            }

            int pos = 0;
            long ans = 0;
            for (int i = 0; i < t.Length; i++)
            {
                int c = t[i] - 'a';

                if (l[pos, c] < 0)
                {
                    Console.WriteLine(-1);
                    return;
                }

                int step = l[pos, c];

                ans += step;
                pos += step;
                pos %= s.Length;
            }

            Console.WriteLine(ans + 1);
        }

    }
}