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 <bits/stdc++.h> 

using namespace std;
using ll=long long;
using ull=unsigned long long;
using pii=pair<int,int>;

#define INF LONG_MAX
#define MOD 1000000007
#define rng(a) a.begin(),a.end()
#define rrng(a) a.end(),a.begin()
#define int ll

signed main(){
  ios::sync_with_stdio(false);
  cin.tie(0);

  string s,t;
  cin>>s>>t;
  int S=s.size();
  int T=t.size();
  map<char,int>m;
  for(auto it:s)m[it]++;
  bool ok=true;
  for(auto it:t)if(!m[it])ok=false;
  if(!ok){
    cout<<-1<<endl;
    return 0;
  }
  vector<map<char,int>>vm(S);
  vm[0]=m;
  for(int i=1;i<S;i++){
    vm[i]=vm[i-1];
    vm[i][s[i-1]]--;
  }
  //for(auto v:vm){for(auto it:v){cout<<it.first<<it.second<<" ";}cout<<endl;}
  map<char,vector<int>>here;
  for(int i=0;i<S;i++)here[s[i]].push_back(i);
  for(auto it:here)sort(rng(it.second));
  map<char,int>memo;
  int now=0;
  ll c=0;
  for(int i=0;i<T;i++){
    //cout<<now<<endl;
    if(vm[now][t[i]]>memo[t[i]]){
      now=here[t[i]][memo[t[i]]];
      memo[t[i]]++;
    }
    else{
      c++;
      now=here[t[i]][0];
      map<char,int>m;
      memo=m;
    }
    //cout<<t[i]<<" "<<now<<" "<<c<<endl;
  }
  //cout<<c<<endl;
  cout<<c*S+now+1<<endl;
  return 0;
}