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 <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <utility>
#include <tuple>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cmath>
#define rep(i, n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int main(){
  string s, t;
  cin >> s >> t;
  int n = s.size();
  s += s;
  vector<vector<int>> next(n, vector<int>(26));
  rep(i, 26) {
    for(int j=n; j<s.size(); j++) {
      if(s[j]-'a' == i) {
        next[n-1][i] = j;
        break;
      }
    }
    for(int j=n-2; j>=0; j--) {
      if(s[j+1]-'a' == i)
       next[j][i] = j+1;
      else
        next[j][i] = next[j+1][i];
    }
  }
  ll ans;
  int now;
  rep(i, n) {
    if(s[i] == t[0]) {
      ans = i+1;
      now = i;
      break;
    }
    if(i == n-1) {
      cout << -1 << endl;
      return 0;
    }
  }
  for(int i=1; i<t.size(); i++) {
    if(!next[now][t[i]-'a']) {
      cout << -1 << endl;
      return 0;
    }
    ans += next[now][t[i]-'a']-now;
    now = next[now][t[i]-'a']%n;
  }
  cout << ans << endl;
  return 0;
}