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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		int N = S.Length;
		String S2 = S + S;
		int N2 = N * 2;
		int[][] min = new int[26][];
		int Inf = (int) 1e9;
		for(int i=0;i<26;i++){
			min[i] = new int[N2];
			for(int j=0;j<N2;j++){
				min[i][j] = Inf;
			}
		}
		for(int j=0;j<26;j++){
			int last = Inf;
			for(int i=N2-1;i>=0;i--){
				if(last != Inf){
					min[j][i] = last - i;
				}
				if(S2[i] == (char) ('a' + j)){
					last = i;
				}
			}
		}
		
//Console.WriteLine(String.Join(" ",min['s' - 'a']));
//Console.WriteLine(String.Join(" ",min['o' - 'a']));
//Console.WriteLine(String.Join(" ",min['n' - 'a']));
		
		
		int strt = -1;
		for(int i=0;i<N;i++){
			if(S[i] == T[0]){
				strt = i;
				break;
			}
		}
		if(strt == -1){
			Console.WriteLine(-1);
			return;
		}
		
		int pos = strt;
		long len = strt + 1;
		for(int j=1;j<T.Length;j++){
			int nstep = min[T[j] - 'a'][pos];
			if(nstep == Inf){
				Console.WriteLine(-1);
				return;
			}
			len += nstep;
			pos += nstep;
//Console.WriteLine("len:{0}, pos:{1}",len, pos);
			if(pos >= N) pos -= N;
		}
		
		Console.WriteLine(len);
		
	}
	String S,T;
	public Sol(){
		S = rs();
		T = rs();
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);}
	static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));}
	static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));}
	static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));}
}