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<bits/stdc++.h>
#define int long long
#define P pair<int,int>
#define PP pair<P,int>
#define F first
#define S second
#define f(i,n) for(int i=0;i<(n);i++)
#define INF LLONG_MAX/3
#define eps LDBL_EPSILON
#define mod (int)(1000000007)
#define pie 3.141592653589793238462643383279
#define Bpri priority_queue
#define Spri priority_queue<P,vector<P>,greater<P>>
#define all(x) (x).begin(),(x).end()
using namespace std;
vector<int> v[26];
int gcd(int a,int b){
	if(b==0)return a;
	return gcd(b,a%b);
}
int lcm(int a,int b){
	return a*b/gcd(a,b);
}
signed main(){
	string s,t;
	cin>>s>>t;
	f(i,s.size()){
		v[s[i]-'a'].push_back(i);
	}
	int z=0,ans=0,vz;
	f(i,t.size()){
		vz=(int)(lower_bound(v[t[i]-'a'].begin(),v[t[i]-'a'].end(),z)-v[t[i]-'a'].begin());
		if(vz==(int)v[t[i]-'a'].size())ans++;
		if(v[t[i]-'a'].size()==0){
			puts("-1");
			return 0;
		}
		z=v[t[i]-'a'][vz%(int)(v[t[i]-'a'].size())];
	}
	cout<<ans*(int)s.size()+z+1<<endl;
}