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();
    HashSet<String> set = new HashSet<String>();
    for(int i = 0; i < t.length(); i++) {
      set.add(String.valueOf(t.charAt(i)));
    }
    ArrayList[] list = new ArrayList[26];
    for(int i = 0; i < 26; i++) {
      list[i] = new ArrayList();
      list[i].add(-1);
    }
    for(int i = 0; i < s.length(); i++) {
      int tt = s.charAt(i) - 'a';
      list[tt].add(i + 1);
    }
    int p = 0;
    for(Iterator<String> i = set.iterator(); i.hasNext();) {
      String str = i.next();
      int tt = (int)str.charAt(0) - 'a';
      if(list[tt].size() == 1) p++;
    }
    if(p > 0) {
      System.out.println(-1);
    } else {
      int slen = s.length();
      int[][] pos = new int[26][slen + 1];
      for(Iterator<String> i = set.iterator(); i.hasNext();) {
        String str = i.next();
        int tt = (int)str.charAt(0) - 'a';
        int h = 1;
        for(int j = 1; j < list[tt].size(); j++) {
          for(int k = h; k <= (int)list[tt].get(j); k++) {
            pos[tt][k] = (int)list[tt].get(j) - k;
          }
          h = (int)list[tt].get(j) + 1;
        }
        for(int k = h; k <= slen; k++) {
          pos[tt][k] = (int)list[tt].get(1) + slen - k;
        }
      }
      int ans = 1;
      for(int i = 0; i < t.length(); i++) {
        int tt = (int)t.charAt(i) - 'a';
        int r = ans % slen;
        if(r == 0) r = slen;
        ans += pos[tt][r];
      }      
      System.out.println(ans);
    }
  }
}