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;
typedef long long ll;

int main(){
    map<char,vector<int>> mp;
    string s,t;
    cin >> s >> t;
    for(int i = 0;i < s.size();i ++){
        mp[s[i]].push_back(i);
    }
    ll j = 0,cnt = -1,pt = 0;
    bool isp = true;
    while(isp && j<t.size()-1){
        map<char,int> cntmp;
        isp = false;
        cnt ++;
        for(int i = j;i < t.size();i ++){
            j = i;
            if(cntmp[t[i]]>=mp[t[i]].size() ||
                (isp && cntmp[t[i]]<mp[t[i]].size() && mp[t[i]][cntmp[t[i]]] <= pt)) break;

            pt = mp[t[i]][cntmp[t[i]]];
            cntmp[t[i]] ++;
            isp = true;
        }
    }
    if(isp) cout << (ll)s.size()*cnt+pt+1ll << endl;
    else    cout << -1 << endl;
    return 0;
}