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;

typedef long long int lli;

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

    string s, t;
    cin >> s >> t;
    int slen = s.size(), tlen = t.size();
    vector<vector<int>> table(slen, vector<int>(26, -1));

    // make table
    for (int alp=0; alp<26; alp++) {
        int cont = -1000000000;
        for (int i=0; i<slen; i++) {
            int idx = slen - i - 1;
            if (s[idx]-'a' == alp) {
                cont = 0;
            }
            table[idx][alp] = cont++;
        }

        for (int i=0; i<slen; i++) {
            int idx = slen - i - 1;
            if (cont < 0 || table[idx][alp] > -1) break;
            table[idx][alp] = cont++;
        }
    }

/*
    for (int i=0; i<3; i++) {
        for (int j=0; j<slen; j++) {
            cout << table[j][i] << " ";
        }
        cout << endl;
    }
*/

    // solve
    lli ans = 1;
    int idx = 0;
    for (int i=0; i<tlen; i++) {
        if (table[idx][t[i]-'a'] < 0) {
            cout << -1 << endl;
            return 0;
        }
        ans += table[idx][t[i]-'a'];
        idx = (idx + table[idx][t[i]-'a']) % slen;
    }

    cout << ans << endl;

    return 0;
}