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: Accepted)

#include <iostream>
#include <fstream>
#include <string>
#include <unordered_map>
#include <stdio.h>
#include <list>
#include <vector>
#include <algorithm>
#include <stack>
#include <climits>
#include <cmath>
#include <map>
#include <queue>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; ++i)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

int main()
{
	string s,t;
	cin >> s >> t;
	int size = s.size();
	s += s;
	vector<vector<int>> alph(26);
	rep(i,s.size())
	{
		alph[s[i]-'a'].push_back(i);
	}
	ll ans = 0;
	ll now = 0;
	rep(i,t.size())
	{
		if(alph[t[i]-'a'].empty())
		{
			cout<<-1<<endl;
			return 0;
		}
		//ans += *upper_bound(ALL(alph[t[i]-'a']),now);
		now = *lower_bound(ALL(alph[t[i]-'a']),now)+1;
		//cout<<now<<endl;
		if(now>=size)
		{
			now-=size;
			ans+=size;
		}
	}
	ans+=now;
	cout<<ans<<endl;
	return 0;
}