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: Wrong Answer)

#include <assert.h>
#include <limits.h>
#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using ll = long long;
using P = std::pair<ll, ll>;

#define rep(i, a, b) for (ll(i) = (a); i < (b); i++)
#define all(i) i.begin(), i.end()
#define debug(i) std::cout << i << "\n"

// const ll MOD = 998244353;
const ll MOD = 1e9 + 7;

int main() {
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  //問題文中の添え字が0-indexか1-indexか確認!

  std::string s,t;
  std::cin>>s>>t;
  bool flag=true;

  ll n=s.size(),m=t.size();

  std::vector<std::vector<ll>> itr(26);

  rep(i,0,m){
    ll  num=t[i]-'a';
    if(!itr[num].size()){
      rep(j,0,n)if(s[j]==t[i])itr[num].push_back(j);
      if(itr[num].empty())flag=false;
    }
  }

  if(!flag){
    std::cout<<-1;
    return 0;
  }

  ll ans=itr[((ll)t[0]-'a')][0]+1;


  ll now=ans-1;
  rep(i,1,m){
    ll next=t[i]-'a';
    if(std::lower_bound(all(itr[next]),now)!=itr[next].end()){
    auto len=std::lower_bound(all(itr[next]),now);
    ans+=(*len-now);
    now=*len;
    }else{
      ans+=(n-now+itr[next][0]);
      now=itr[next][0];
    }

    //debug(now);
    //debug(ans);
  }

  std::cout<<ans;

  return 0;
}