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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <limits.h>
#include <math.h>
int acs(const void *a, const void *b) { return *(int *)a - *(int *)b; }                            /* 1,2,3,4.. */
int des(const void *a, const void *b) { return *(int *)b - *(int *)a; }                            /* 8,7,6,5.. */
int cmp_char(const void *a, const void *b) { return *(char *)a - *(char *)b; }                     /* a,b,c,d.. */
int cmp_str(const void *a, const void *b) { return strcmp(*(const char **)a, *(const char **)b); } /* aaa,aab.. */
#define min(a, b) (a < b ? a : b)
#define max(a, b) (a > b ? a : b)

typedef long long int lli;

int main(void)
{
  char s[100001], t[100001];
  int al[26][100001];

  scanf("%s", s);
  scanf("%s", t);

  int s_len = strlen(s);
  int t_len = strlen(t);

  int si, ti, ch;
  for (si = 0; si < s_len; si++)
  {
    ch = (int)(s[si] - 'a');
    for (ti = si; ti >= 0 && al[ch][ti] == 0; ti--)
      al[ch][ti] = si;
  }

  for (ch = 0; ch < 26; ch++)
  {
    for (si = s_len - 1; si >= 0 && al[ch][ti] == 0; si--)
      al[ch][si] = al[ch][0];
  }

  lli ans = 1;
  int now;
  for (ti = 0; ti < t_len; ti++)
  {
    ch = (int)(t[ti] - 'a');
    now = ans % s_len - 1;
    si = al[ch][now + 1];
    if (si == 0)
    {
      ans = -1;
      break;
    }
    else
    {
      if (si > now)
        ans += si - now;
      else
        ans += s_len + si - now;
    }
  }

  printf("%lld\n", ans);

  return 0;
}