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;//list用
using System.Text;//StringBuilder用
using System.Collections;//ハッシュテーブル用
using System.Linq;
class Program
{
    Hashtable ht = new Hashtable();
    static string S,T;
  static List<decimal>[] alpha=new List<decimal>[26];
  static decimal result;
    static StringBuilder str1= new StringBuilder("");//Append(str ○○)関数で文字を追加していく

    static void Main()
    {
        Read1();
      //S上で登場する文字の位置をリストalpha[]に保存(aは何文字目と何文字目に出て，bは…という感じ）
      Alpha();
      decimal[] check=new decimal[T.Length];
      decimal[] k=new decimal[26];
      bool dame;
for(int i=0;i<T.Length-1;i++){
  dame=false;
      //T[i]をalphaに対応させて番号を振っていく
for(int j=0;j<26;j++){
if(T[i]=='a' + j){
  if(k[j]>=alpha[j].Count){
    result+=S.Length;
    for(int x=0;x<26;x++){k[x]=0;}
    //このケースではcheckの判定をさせない。（checkでresultを足すと２重カウントになってしまう）
    dame=true;
                           }
if(alpha[j].Count==0){Console.WriteLine("-1");return;}
                  check[i]=alpha[j][(int)k[j]];k[j]++;}
}
  if(i==0){continue;}
  if(i==T.Length-1){break;}
    //checkの中身が一個前より小さくなったらresultにS.Lengthを足し，kをリセット（逆順になる＝もう一度S先頭に戻るということ）
  if(check[i]<=check[i-1] && dame==false){result+=S.Length;for(int j=0;j<26;j++){k[j]=0;}}
}
for(int j=0;j<26;j++){ if(T[T.Length-1]=='a' + j){if(alpha[j].Count==0){Console.WriteLine("-1");return;} if(k[j]>=alpha[j].Count){k[j]=0;}check[T.Length-1]=alpha[j][(int)k[j]];}}
  //check[T.Length-1]の中身の数字をresultに足す
  result+=check[T.Length-1];
      //０文字目からで計算してるので，スタートを１文字目とカウント
      result++;
        Console.WriteLine(result.ToString());
    }

    static void Read1()
    {
        S = Console.ReadLine();
        T = Console.ReadLine();
    }
static void Alpha()
{
  for(int j=0;j<26;j++){alpha[j]=new List<decimal>();}
for(int i=0;i<S.Length;i++)
{
  for(int j=0;j<26;j++){
if(S[i]=='a' + j){alpha[j].Add(i);}
  }
}
}
  
  

}