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)

//code by lynmisakura.wish to be accepted
/****************************/
#include<iostream>
#include<math.h>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<algorithm>
#include<bitset>
#include <climits>
#include<set>
#include<bitset>
using namespace std;
/***************************/
typedef long long ll;
typedef pair<int,int> pi;
typedef vector<pair<int,int>> vpi;
 
const long long Mod = 998244353;
const long long mod = 1000000007;
const long long INF = 10000000000000;
 
#define itn int
#define endl "\n"
#define pb push_back
#define mp make_pair
#define mins(x,y) x = min(x,y)
#define maxs(x,y) x = max(x,y)
#define all(x) (x).begin(),(x).end()
#define Rep(n) for(int i = 0;i < n;i++)
#define rep(i,n) for(int i = 0;i < n;i++)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() )
 
ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
ll qp(ll a, ll b) { int ans = 1; do { if (b & 1)ans = 1ll * ans*a; a = 1ll * a*a; } while (b >>= 1); return ans; }
ll qp(ll a, ll b, int mo) { int ans = 1; do { if (b & 1)ans = 1ll * ans*a%mo; a = 1ll * a*a%mo; } while (b >>= 1); return ans; }
 
#define _GLIBCXX_DEBUG
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
 
 
int main(void){
	
	string s,t; cin >> s >> t;
	ll n = s.size();
	ll m = t.size();
	//sの各文字がいつ現れるかを持っておく
	vector<vector<ll>> ch(26,vector<ll>(0));
	rep(i,n) ch[s[i] - 'a'].pb(i);
	rep(i,n) ch[s[i] - 'a'].pb(i + n);
	
	ll ans = 0LL;
	ll p = 0LL;
	rep(i,m){
		if(ch[t[i]-'a'].size() == 0){
			cout << -1 << endl;
			return 0;
		}
		p = *lower_bound(all(ch[t[i]-'a']),p);
		if(p >= n){
			p -= n;
			ans += n;
		}
	}
	cout << ans + p + 1LL << endl;
	return 0;
}