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: Accepted)

#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define ALL(a)  (a).begin(),(a).end()
#define PI 3.14159265358979
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
const ll mod = 1e9+7LL;

int main() {
    string s, t; cin >> s >> t;
    ll ans = 0;

    map<char, vector<int>> d;
    rep(i, s.size()){
        d[s.at(i)].push_back(i);
    }
    
    ll now = -1;
    ll loop = 0;
    rep(i, t.size()){
        if(!d.count(t.at(i))){
            cout << -1 << endl;
            return 0;
        }
        if(now>=d.at(t.at(i)).at(d.at(t.at(i)).size()-1)){
            loop++;
            now = d.at(t.at(i)).at(0);
            continue;
        }
        auto iter = upper_bound(ALL(d.at(t.at(i))), now);
        now = *iter;
    }
    ans += loop*s.size() + now + 1;
    cout << ans << endl;
}