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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.util.*;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    String s = sc.next();
    String t = sc.next();

    char[] sChar = s.toCharArray();
    Map<Character, Alphabet> map = new HashMap<>();

    // Map生成
    for (int i = 0; i < sChar.length ; i++) {
      Alphabet a = map.get(sChar[i]);
      if (a == null) {
        map.put(sChar[i], new Alphabet(sChar[i], i));
      } else {
        a.addIndex(i);
      }
    }

    char[] tChar = t.toCharArray();

    int position = -1;
    long count = 0;
    int sCharLength = sChar.length;

    for(int i = 0; i < tChar.length ; i++){
      //System.out.print("index: i " + i + ", Alphabet:" + tChar[i] + ", Count:" + count);
      Alphabet a = map.get(tChar[i]) ;
      if(a == null){
        count = -1;
        break;
      }
      int nextIndex = a.nextIndex(position);
      //System.out.println(", "+ nextIndex + "," + position);
      if(nextIndex <= position){
        count += (sCharLength - position) + nextIndex;
      } else {
        count += nextIndex - position;
      }
      position = nextIndex;
    }

    System.out.println(count);
  }

  public static class Alphabet {
    char alphabet;
    int[] a;
    public Alphabet (char c, int index){
      this.alphabet = c;
      int[] tmp = {index};
      this.a = tmp;
    }

    public void addIndex (int index){
      int[] tmp = new int[a.length + 1];
      System.arraycopy(a, 0, tmp, 0, a.length);

      tmp[a.length] = index;
      a = tmp;
    }

    public int nextIndex(int index){
      if(a[a.length - 1] < index){
        return a[0];
      }
      int pos = -1;
      int lower = 0; // 下限
      int upper = a.length - 1; // 上限
      int mid = 0;

      while (lower <= upper) {

        mid = (lower + upper) / 2;
          if (a[mid] == index) {
            pos = mid;
            break;
          } else if (a[mid] < index) {
            lower = mid + 1;
          } else {
            upper = mid - 1;
          }
       }
      if(mid - 1 >=  0 && a[mid - 1] > index){
        return a[mid - 1];
      } else if (a[mid] > index){
        return a[mid];
      } else{
        return a[mid + 1];
      }
    }
  }
}