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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <cstdio>
#include <iostream>
#include <queue>
#include <set>
#include <vector>
#include <cstring>
#include <algorithm>

int main(){
  
  // read problem
  char s[100001], t[100001];
  long long int s_len, t_len;
  scanf("%s", s);
  scanf("%s", t);
  s_len = strlen(s);
  t_len = strlen(t);
  
  std::vector< std::vector<long long int> > s2_list(26);
  for(int i = 0; i < s_len; i++){
    s2_list[(int)s[i] - 'a'].push_back(i);
  }
  for(int i = 0; i < s_len; i++){
    s2_list[(int)s[i] - 'a'].push_back(i+s_len);
  }
  
  // solve probelm
  long long int sprime_len = 0;
  long long int current_index = s_len-1;
  long long int difference;
  int flag = 1;
  
  for(long long int i = 0; i < t_len; i++){
    if(s2_list[(int)t[i] - 'a'].size() == 0){
      flag = 0;
      break;
    }
    
    difference = *(std::upper_bound(s2_list[(int)t[i]-'a'].begin(), s2_list[(int)t[i]-'a'].end(), current_index)) - current_index;
    sprime_len += difference;
    current_index += difference;
    current_index %= s_len;
  }
  
  if(flag==0){
    std::cerr << "Answer:" << std::endl;
    std::cout << "-1" << std::endl;
  }
  else{
    std::cerr << "Answer: " << std::endl;
    std::cout << sprime_len << std::endl;
  }
  
  return 0;
}