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 <iostream>
#include <math.h>
#include <fstream>
#include <algorithm>
#include <string>
#include <string.h>
#include <queue>
#include <vector>
#include <set>
#include <map>
using namespace std;
long long int euclidean_gcd(long long int a, long long int b) {
	if (a < b) return euclidean_gcd(b, a);
	long long int r;
	while ((r = a%b)) {
		a = b;
		b = r;
	}
	return b;
}
int main() {
	string s, t;
	cin >> s >> t;
	vector<vector<int>>A(26);
	for (int i = 0; i < s.size(); i++)A[s[i] - 'a'].push_back(i);
	long long int a = 0, ans = 0;
	bool flag = true;
	for (int i = 0; i < t.size();)
	{
		int k = t[i] - 'a';
		if (A[k].size() == 0) {
			flag = false;
			break;
		}
		if (i == 0) {
			ans=A[k][0];
			i++;
		}
		else {
			if (A[k][A[k].size() - 1] < ans) {
				ans = A[k][0];
				i++;
				a++;
			}
			else
			{
				auto it = std::lower_bound(A[k].begin(), A[k].end(), ans);
				ans = *it;
				i++;
			}
			
		}
	}
	if (flag)cout << 1 + ans + a*s.size();
	else cout << -1;
}