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 Rust (1.42.0) (judge verdict: Accepted)

// -*- coding:utf-8-unix -*-

use proconio::input;
use ascii::AsciiString;
use ascii::AsciiChar;

// ABC086C - Traveling
// https://atcoder.jp/contests/abs/fasks/arc089_a

fn main() {
    input! {
        s :AsciiString,
        t :AsciiString,
    }

    let slen :usize = s.len();
    let tlen :usize = t.len();

    let mut skip_table :Vec<Vec<isize>> = vec![vec![-1;slen];26];
    for i in 0..26 {
        let mut last_match :isize = -1;
        for j in 0..slen {
            if (s[slen-1-j].as_byte() - AsciiChar::from_ascii('a').unwrap().as_byte()) as usize == i {
                last_match = (slen-1-j) as isize;
            }
            if last_match != -1 {
                skip_table[i][slen-1-j] = last_match - ((slen-1-j) as isize);
            }
        }
        for j in 0..slen {
            if (s[slen-1-j].as_byte() - AsciiChar::from_ascii('a').unwrap().as_byte()) as usize == i {
                last_match = (slen-1-j) as isize;
            }
            if (last_match != -1) && (last_match < ((slen-1-j) as isize)) {
                skip_table[i][slen-1-j] = last_match + (slen as isize) - ((slen-1-j) as isize);
            }
        }
    }
    let mut i :usize = 0;
    for j in 0..tlen {
        let nowchar = (t[j].as_byte() - AsciiChar::from_ascii('a').unwrap().as_byte()) as usize;
        if skip_table[nowchar][i%slen] == -1 {
            println!("-1");
            return;
        }
        i += skip_table[nowchar][i%slen] as usize;
        i += 1;
    }
    println!("{}", i);
}