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 <vector>
#include <algorithm>
#include <stack>
#include <queue>
#include <list>
#include <string>
#include <numeric>
#include <math.h>
#include <set>
#include <map>
#include <fstream>
#include <sstream>
#include <iterator>
#include <complex>
using namespace std;

int main()
{
	string s,t;

	cin>>s>>t;
	int s_size = s.size();
	int t_size = t.size();

	vector<vector<int> > mt(26);
	for(int i=0; i<s_size; i++)
	{
		int index = s[i] - 'a';
		mt[index].push_back(i);
	}

	long long count = 1;
	int s_index = 0;
	for(int i=0; i<t_size; i++)
	{
		int t_index = t[i] - 'a';
		//tにsに含まれない文字があった場合はその時点で終了
		if(mt[t_index].size() == 0)
		{
			cout<<-1<<endl;
			return 0;
		}
		auto it = upper_bound(mt[t_index].begin(),mt[t_index].end(), s_index);
		
		
		//cout<<endl;
		//cout<<t[i]<<":";
		if(it == mt[t_index].end() || *it <= s_index)
		{
			//cout<<"up:"<<s_size - s_index + mt[t_index][0]<<endl;
			count +=  s_size - s_index + mt[t_index][0];
			s_index = mt[t_index][0];
			
		}
		else
		{
			//cout<<"down:"<<*it - s_index<<endl;
			count += *it - s_index;
			s_index = *it;
			
		}
		

	}
	cout<<count<<endl;

}