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)

/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author HARSHAD
 */

#include <bits/stdc++.h>


#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define int long long

using namespace std;

class EStringsOfImpurity {
public:
    void solve(std::istream &in, std::ostream &out) {
        string s, t;
        in >> s >> t;
        int n = s.length();
        unordered_map<char, vector<int>> Map;
        for (int i = 0; i < n; ++i) Map[s[i]].push_back(i);

        int res = 0, ind = -1;

        for (int i = 0; i < t.length(); ++i) {
            if (Map[t[i]].empty()) {
                res = -1;
                break;
            }
            auto nxt = upper_bound(Map[t[i]].begin(), Map[t[i]].end(), ind);
            if (nxt == Map[t[i]].end()) res += (n - ind), nxt = Map[t[i]].begin(), ind = *nxt, res += ind;
            else res += (*nxt - ind), ind = *nxt;
        }
        out << res;
    }
};


int32_t main() {
    EStringsOfImpurity solver;
    std::istream &in(std::cin);
    std::ostream &out(std::cout);
    solver.solve(in, out);
    return 0;
}