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 std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;
using std::bitset;

#define rep(i,n)    for(int i=0; i<(int)n; i++)
#define reps(i,s,e) for(int i=s; i<(int)e; i++)
#define coutd(i) cout << std::fixed << std::setprecision(i)
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef std::pair<int, int> pii;
typedef std::pair<ll, ll> pll;

template<class T>
using Set = std::set<T>;
template<class T, class U>
using Map = std::map<T, U>;

template<class T>
using Graph = vector<vector<T>>;

const int INT_BIG = 1<<28;

int main() {
    string s, t;
    cin >> s >> t;
    int slen = s.length();
    Map<char, vll> cmap;
    rep(i, slen) {
        char c = s[i];
            
        cmap[c].push_back(i);
    }

    ll ans = 1;
    int nowpos = -1;
    int tlen = t.length();
    rep(i, tlen) {
        char c = t[i];
        if (cmap.find(c) == cmap.end()) {
            cout << -1 << endl;
            return 0;
        }

        int cmapvlen = cmap[c].size();
        // cout << "c" << c << cmap[c][0] << endl;
        if (nowpos > cmap[c][cmapvlen - 1]) {
            ans++;
            nowpos = cmap[c][0];
        } else if (nowpos < cmap[c][0]) {
            nowpos = cmap[c][0];
        } else {
            int left = -1;
            int right = cmapvlen;
            while ((right - left) > 1) {
                int mid = left + (right - left) / 2;
                if (cmap[c][mid] <= nowpos) {
                    left = mid;
                } else {
                    right = mid;
                }
            }
            nowpos = right;
        }
        // cout << nowpos << endl;
    }
    cout << (ans-1)*slen + nowpos + 1 << endl;
}