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.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC138_E
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = Console.ReadLine();
            var t = Console.ReadLine();

            var alphaS = new List<int>[26];
            var alphaT = new List<int>[26];

            for (int i = 0; i < 26; i++)
            {
                alphaS[i] = new List<int>();
                alphaT[i] = new List<int>();
            }

            for (int i = 0; i < s.Length; i++)
            {
                var c = (int)s[i] - 97;
                alphaS[c].Add(i + 1);
            }

            for (int i = 0; i < t.Length; i++)
            {
                var c = (int)t[i] - 97;
                alphaT[c].Add(i + 1);
            }

            var ans = long.MaxValue;

            var last = 0;
            var temp = 0;
            var failed = false;

            var si = new int[s.Length];
            for (int i = 0; i < s.Length; i++)
            {
                var c = (int)s[i] - 97;
                if (alphaT[c].Count == 0)
                {
                    failed = true;
                    break;
                }

                si[i] = alphaT[c].Where(x => x > last).FirstOrDefault();
                if (si[i] == 0)
                {
                    temp += t.Length;
                    si[i] = alphaT[c].First();
                }
                last = si[i];
            }
            if (!failed)
            {
                temp += last;
                ans = temp;
            }

            last = 0;
            temp = 0;
            failed = false;

            var ti = new int[t.Length];
            for (int i = 0; i < t.Length; i++)
            {
                var c = (int)t[i] - 97;
                if (alphaS[c].Count == 0)
                {
                    failed = true;
                    break;
                }

                ti[i] = alphaS[c].Where(x => x > last).FirstOrDefault();
                if (ti[i] == 0)
                {
                    temp += s.Length;
                    ti[i] = alphaS[c].First();
                }
                last = ti[i];
            }
            if (!failed)
            {
                temp += last;
                ans = Math.Min(temp, ans);
            }

            Console.WriteLine(ans == long.MaxValue ? -1 : ans);

        }
    }
}