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;
using ll = long long;
#define int ll
signed main(){
    string s; cin >> s;
    string t; cin >> t;
    map<char,int>schars,tchars,nextIndex;
    for(auto c : s)schars[c]++;
    for(auto c : t)tchars[c]++;
    for(auto itr : tchars)
        if(schars[itr.first] == 0) return puts("-1") * 0;
    vector<vector<int>> pos(26);
    for(int i = 0; i < s.size(); ++i)
        pos[s[i] - 'a'].push_back(i);
    int ans = 0;
    int nowIndex = -1;
    int ssize = s.size();
    for(auto c : t){
        char key = c - 'a';
        auto itr = (upper_bound(pos[key].begin() + nextIndex[key],pos[key].end(),nowIndex));
        if(itr != pos[key].end()){
            ans +=  *itr - nowIndex;
        } else {
            itr = pos[key].begin();
            ans += ssize - nowIndex + pos[key].front();
        }
        nowIndex = *itr;
        nextIndex[key] = (next(itr) == pos[key].end() ? 0 :( next(itr) - pos[key].begin()));
    }
    cout << ans << endl;
}