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: Time Limit Exceeded)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
  static void Main()
  {
    string s = Console.ReadLine();
    string t = Console.ReadLine();
    var chdic = new Dictionary<string, Queue<int>>();
    
    for (int i = 0; i < s.Length; i++){
      string c = s.Substring(i, 1);
      if (chdic.ContainsKey(c))
        chdic[c].Enqueue(i);
      else{
        chdic.Add(c, new Queue<int>());
        chdic[c].Enqueue(i);
      }
    }
    
    long point = -1;
    for (int i = 0; i < t.Length; i++){
      string c = t.Substring(i, 1);
      
      if (!chdic.ContainsKey(c)){ // s に c が含まれない場合
        point = -2;
        break;
      }
      
      while(true){
        int first = chdic[c].Dequeue();
        chdic[c].Enqueue(first + s.Length);
        
        if (first > point){
          point = first;
          break;
        }
      }
    }
    
    Console.WriteLine(point + 1);
    
  }
  
}