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>
using namespace std;
#define FOR(i,n) for(int i=0;i<(n);i++)
#define MOD 1000000007
#define all(n) (n).begin(),(n).end()
typedef long long ll;
template <class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}else{return 0;}}
template <class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}else{return 0;}}
template <class T> inline T GCD(T a,T b){T c;while(b!=0){c=a%b;a=b;b=c;}return a;}
template <class T> inline T LCM(T a,T b){return a*b/GCD(a,b);}

int main(){
	string s,t;
	cin >> s >> t;
	vector<ll> v[50];

	FOR(i,s.size()){
		v[s[i]-'a'].push_back((ll)i);
		v[s[i]-'a'].push_back((ll)i+(ll)s.size());
	}
	bool aaa=1;
	FOR(i,t.size()){
		if(v[t[i]-'a'].empty())aaa=0;
	}

	if(aaa){
		ll cnt=0;
		ll ans=0;
		FOR(i,t.size()){
			auto itr=lower_bound(all(v[t[i]-'a']),cnt);
			ans+=*itr-cnt;
			cnt=*itr;
			cnt%=(ll)s.size();

		}

		cout << ans+1 << endl;

	}else{
		cout << -1 << endl;
	}
}