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 <iostream>
#include <iomanip>
#include <queue>
#include <deque>
#include <cstring>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <cmath>
#include <bitset>

#define REP(i, n) for(int i = 0, i##_len = (n); i < i##_len; ++i)
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define FILL(x, y) memset(x, y, sizeof(x))
#define pb push_back
#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif

template<class T>bool chmax(T &a, const T &b) {
   if (a < b) {
      a = b;
      return 1;
   }
   return 0;
}
template<class T>bool chmin(T &a, const T &b) {
   if (a > b) {
      a = b;
      return 1;
   }
   return 0;
}

using namespace std;
using ll = long long;

const int kInf = 2e9;
const ll kLInf = 2e18;

int gcd (int a, int b) {
   return b ? gcd(b, a % b) : a;
}
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
string s,t;
set<int> pos[26];
int nextList[30][1000010];

int main()
{
   cout << fixed << setprecision(10);
   cin >> s >> t;
   REP(i, SZ(s)) {
      pos[s[i]-'a'].insert(i+1);
   }
   REP(i, SZ(t)) {
      if (!SZ(pos[t[i]-'a'])) {
         cout << -1 << endl;
         return 0;
      }
   }
   REP(i, 26) {
      if (!SZ(pos[i])) continue;
      auto itr = pos[i].end();
      itr--;
      REP(j, SZ(s)) nextList[i][j] = *itr;
      while (1) {
         REP(j, *itr) nextList[i][j] = *itr;
         if (itr == pos[i].begin()) break;
         itr--;
      }
   }
   ll times = 0;
   ll prev = SZ(s)-1;
   REP(i, 26) {
      eprintf("%c: ", 'a'+i);
      REP(j, SZ(s)) eprintf("%d ", nextList[i][j]);
      eprintf("\n");
   }
   REP(i, SZ(t)) {
      eprintf("%c: ", t[i]);
      ll nextPos = nextList[t[i]-'a'][prev];
      if (nextPos <= prev && i) {
         times++;
      }
      prev = nextPos;
      eprintf("prev %lld, times %lld\n", prev, times); 
   }
   cout << SZ(s) * times + prev << endl;
   return 0;
}