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>
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.. */

#define MAXN (100000)

char s[MAXN+1];
char t[MAXN+1];

int ci[26][MAXN];



int main(void)
{
    scanf("%s",s);
    scanf("%s",t);
    int slen = strlen(s);
    int tlen = strlen(t);

    for(int i=0;s[i]!='\0';i++){
        for(int j=i; (ci[s[i]-'a'][j]==0)&& j>=0; j--)
        {
            ci[s[i]-'a'][j] = i+1;
        }
    }
    for(int i=0;i<26;i++)
    {
        for(int j=slen-1;(ci[i][j]==0)&& j>=0; j--)
        {
            ci[i][j] = ci[i][0];
        }
    }

    // for(int i=0;i<26;i++)
    // {
    //     printf("%c: ",'a'+i);
    //     for(int j=0;j<slen;j++)
    //     {
    //         printf("%d ",ci[i][j]);
    //     }
    //     printf("\n");
    // }
    uint64_t ans = 0;
    int ni = slen-1;
    for(int i=0;t[i]!='\0';i++){
        int ti = ci[t[i]-'a'][ni];
        if(ti==0)
        {
            printf("-1\n");
            return 0;
        }
        ti--;
        if(ti > ni)
        {
            ans += ti - ni;
        }else
        {
            ans += slen + ti - ni;
        }
        // printf("%d %d %ld\n", ni, ti, ans);
        ni = ti;
    }
    printf("%ld\n",ans);
    return 0;
}