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: Time Limit Exceeded)

#include <bits/stdc++.h>
using namespace std;

long solve(string s, string t) {
    long ans = 0;
    unordered_map<char, vector<int> > mp;
    const long s_size = s.size();
    for (int i = 0; i < s_size; i++) {
        mp[s[i]].push_back(i + 1);
    }
    int p = 0;
    for (int i = 0; i < t.size(); i++) {
        if (mp.find(t[i]) == mp.end())
            return -1;
        vector<int> v = mp[t[i]];
        int ub = upper_bound(v.begin(), v.end(), p) - v.begin();
        if (ub == v.size()) {
            p = v[0];
            ans += s_size;
        } else {
            p = v[ub];
        }
    }
    ans += p;
    return ans;
}

int main() {
    string s, t;
    cin >> s >> t;
    cout << solve(s, t) << endl;
    return 0;
}