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 <bits/stdc++.h>
using namespace std;
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
#define REP(i,n) for(int i=0;i<(int)(n);i++)
using ll=long long;

vector<ll> indices[26];

void solve(std::string s, std::string t){
  ll sSize=s.size();
  REP(i,(int)sSize){
    int c=s[i]-'a';
    indices[c].push_back(i);
  }
  ll tSize=t.size();
  ll count=0;
  ll last=0;
  REP(i,(int)tSize){
    int c=t[i]-'a';
    if(indices[c].size()==0){
      cout<<"-1"<<endl;
      return;
    }
    auto idx=lower_bound(indices[c].begin(),indices[c].end(),last);
    if(idx==indices[c].end()){
      count++;
      idx=indices[c].begin();
    }
    last=*idx;
    last++;
  }
  cout<<count*sSize+last<<endl;
}

int main(){_;
  std::string s;
  std::cin >> s;
  std::string t;
  std::cin >> t;
  solve(s, t);
  return 0;
}