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# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;

class MainClass
{
    static void Main()
    {
        string s = ReadLine();
        string t = ReadLine();

        string S = s + s;
        var next = new long[26][];
        for (int i = 0; i < 26; i++)
        {
            next[i] = Enumerable.Repeat((long)1e11, s.Length).ToArray();
            int now = 0;
            int point = 0;
            while (now < S.Length&&point<s.Length)
            {
                while (now < S.Length && S[now] != 'a' + i) now++;
                if (now < S.Length)
                {
                    for (int j = Min(s.Length-1,now); j >=point; j--)
                    {
                        next[i][j] = Min(next[i][j],now - j);
                    }
                    point = now;
                    now++;
                }
            }
        }
        long ans = 0;
        long sindex = 0;
        for (int i = 0; i < t.Length; i++)
        {
            var v = next[t[i] - 'a'][sindex]+1;
            if (v == (long)1e11)
            {
                WriteLine(-1);
                return;
            }
            ans += v;

            sindex = (sindex + v) % s.Length;
        }
        WriteLine(ans);
    }
}