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;

int main()
{
    string S,T;
    cin>>S>>T;
    const int LETTER=26;
    vector<vector<long long int>>location(LETTER);
    for(int i=0;i<S.length();i++)
    {
        location[S[i]-'a'].push_back(i);
    }
    long long int cnt=0 , last_loc=-1 , last_len=-1 ;
    for(int i=0;i<T.length();i++)
    {
        if(location[T[i]-'a'].size()==0)
        {
            cout<<"-1";
            return 0;
        }
        auto itr=upper_bound(location[T[i]-'a'].begin(),location[T[i]-'a'].end(),last_loc);
        if(itr==location[T[i]-'a'].end())
        {
            cnt++;
            last_loc=location[T[i]-'a'][0];
        }
        else
        {
            if(i==T.length()-1)
                last_len= *itr;
            last_loc=*itr;
        }
    }
    long long total_length=cnt*S.length()+last_len+1;
    cout<<total_length<<endl;
    return 0;
}