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 FOR(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define FORUL(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#define FORULE(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define FOREACH(it, X) for(__typeof((X).begin()) it = (X).begin(); it != (X).end(); it++)
#if defined(_MSC_VER) || __cplusplus > 199711L
#define AUTOVAR(newvar,v) auto newvar = (v)
#else
#define AUTOVAR(newvar,v) __typeof(newvar) r = (v)
#endif
#define PB(x) push_back(x)
#define MP(x,y) make_pair((x),(y))
#define MEMSET(m,v) memset(m,v,sizeof(m))

typedef long long				 ll;
typedef unsigned long long		ull;

#define DEBUG 1

#if DEBUG
#define DOUT cout<<"["<<__LINE__<<"]:"
#else
#define DOUT 0 && cout
#endif

using namespace std;

string s;
string t;
vector<vector<int> > posvec;

int main(int argc, char *argv[])
{
	ios::sync_with_stdio(false);

	cin >> s;
	cin >> t;

	posvec.resize(26);

	FOR(i,s.size()) {
		posvec[s[i]-'a'].push_back(i);
	}
	FOR(i,s.size()) {
		posvec[s[i]-'a'].push_back(i+s.size());
	}
	int pos = 0;
	ll ans = 0;
	string::iterator it_t = t.begin();
	for(;it_t!=t.end();it_t++) {
		if(posvec[(*it_t)-'a'].size()==0) {
			cout << -1 << endl;
			return 0;
		}
		pos = *lower_bound(
				posvec[(*it_t)-'a'].begin(),
				posvec[(*it_t)-'a'].end(),
				pos)+1;
		if(pos>=s.size()) {
			pos -= s.size();
			ans += s.size();
		}
	}

	ans += pos;
	cout << ans << endl;

	return 0;
}