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)

/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author lstd
 */

#include <iostream>
#include <fstream>

#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <bitset>
#include <random>
#include <chrono>
#include <complex>
#include <algorithm>
#include <utility>
#include <functional>
#include <cmath>
#include <cstring>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <ctime>

using namespace std;

#define sqr(x) ((x)*(x))
#define mp make_pair
#define pb push_back
#define FOR(i,a,b) for (int i = (a); i <= (b); i++)
#define RE(i, n) FOR(i,1,n)
#define REP(i,n) FOR(i, 0, (int)(n)-1)
#define fst first
#define snd second

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, int> pli;
typedef pair<ll, ll> pll;
typedef long double ld;

string to_string(string s) {
    return '"' + s + '"';
}

string to_string(const char* s) {
    return to_string((string) s);
}

string to_string(bool b) {
    return (b ? "true" : "false");
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for (const auto &x : v) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}



void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}

int XMOV[4] = {0, 0, 1, -1};
int YMOV[4] = {1, -1, 0, 0};

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

using namespace std;

class EStringsOfImpurity {
public:
	void solve(std::istream& in, std::ostream& out) {
		string s, t;

		in >> s >> t;

		map<char, vector<int>> sc, tc;
		for (int i = 0; i < s.size(); i++)
			sc[s[i]].pb(i);

		bool flag = true;
		for (int i = 0; i < t.size(); i++)
			if (sc.count(t[i]) == 0)
				flag = false;

		if (!flag){
			out << -1;
			return;
		}

		int carry = 0, lastidx = -1;
		for (int i=0; i < t.size(); i++){
			int cur;
			auto idx = upper_bound(sc[t[i]].begin(), sc[t[i]].end(), lastidx);
			if (idx != sc[t[i]].end()){
				cur = *idx;
			}
			else{
				carry++;
				cur = sc[t[i]][0];
			}
			lastidx = cur;

		}

		out << carry*s.size()+lastidx+1;
	}
};

int main() {
	EStringsOfImpurity solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}