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;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

string s, t;

int main() {
    cin >> s >> t;
    int slen = s.length(); int tlen = t.length();

    vector<int> salp(26, 0);
    vector< vector<int> > spos(26, vector<int>());
    for(int i = 0; i < slen; ++i) {
        int alpin = s.at(i) - 'a';
        salp.at(alpin)++;
        spos.at(alpin).emplace_back(i);
    }

    set<char> tst;
    for(int i = 0; i < tlen; ++i) tst.insert(t.at(i));

    bool flg = true;
    for(auto x : tst) {
        int talp = x - 'a';
        if(salp.at(talp) == 0) {
            flg = false;
            break;
        }
    }

    if(!flg) {
        cout << -1 << endl;
    }else {
        long long cnt = 0;
        int now = -1;
        for(int i = 0; i < tlen; ++i) {
            char check = t.at(i);
            int tch = check - 'a';
            // cout << "t " << tch << endl;
            bool fflg = false;
            // cout << "tlen " << spos.at(tch).size() << endl;
            for(int j = 0; j < (int)spos.at(tch).size(); ++j) {
                int cc = spos.at(tch).at(j);
                // cout << "ok" << endl;
                if(now < cc) {
                    now = cc;
                    fflg = true;
                    break;
                }
            }
            if(!fflg) {
                now = spos.at(tch).at(0);
                cnt++;
            }
            // cout << "cnt " << cnt << " now " << now << endl;
        }

        cout << (long long)slen * cnt + now + 1 << endl;
    }
}