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 (1.15.1) (judge verdict: Wrong Answer)

fn main() {
    let s = read::<String>();
    let t = read::<String>();
    let mut ans = 0;

    let s_len = s.len();
    let t_len = t.len();

    let s_vec: Vec<char> = s.chars().collect();

    let mut t_marker = vec![];
    'outer: for c in t.chars() {
        'inner: for i_s in 0..s_len {
            if s_vec[i_s] == c {
                t_marker.push(i_s);
                continue 'outer;
            }
        }

        println!("-1");
        return;
    };

    let mut prev_index = t_marker[0];
    let mut flg = false;
    for i in 1..t_len {
        if prev_index >= t_marker[i] {
            ans += s_len;
            flg = true;
        }
        else {
            flg = false;
        }
        prev_index = t_marker[i]
    }
    if flg == false {
        ans += t_marker[t_len-1] + 1;
    }

    println!("{}", ans);
}

#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T  {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().parse::<T>().ok().unwrap()
}

#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
    .map(|e| e.parse().ok().unwrap())
    .collect()
}