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)

// E - Strings of Impurity
#include <bits/stdc++.h>

using namespace std;

int main(int argc, char *argv[])
{
	string s, t;
	cin >> s >> t;

	set<char> x;
	for (int i = 0; i < s.size(); i++) x.insert(s[i]);
	bool failed = false;
	for (int i = 0; i < t.size(); i++)
		if (x.count(t[i]) == 0)
			failed = true;
	if (failed) {
		cout << -1 << endl;
		return 0;
	}

	x.clear();
	for (int i = 0; i < t.size(); i++) x.insert(t[i]);

	string z;
	vector<long long> p;
	for (int i = 0; i < s.size(); i++)
		if (x.count(s[i]) > 0) {
			z += s[i];
			p.push_back(i);
		}

	long long ans = 0;
	for (int i = 0, j = 0, jj = -1; i < t.size(); i++)
		for ( ; ; j = (j + 1) % z.size())
			if (z[j] == t[i]) {
				ans += p[j] - (jj >= 0 ? p[jj] : 0);
				if (j <= jj) ans += s.size();
				jj = j;
				j = (j + 1) % z.size();
				break;
			}

	cout << ans + 1 << endl;

	return 0;
}