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: Time Limit Exceeded)

macro_rules! get {
    ($t:ty) => {
        {
            let mut line: String = String::new();
            std::io::stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t:ty),*) => {
        {
            let mut line: String = String::new();
            std::io::stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            (
                $(iter.next().unwrap().parse::<$t>().unwrap(),)*
            )
        }
    };
    ($t:ty; $n:expr) => {
        (0..$n).map(|_|
                    get!($t)
        ).collect::<Vec<_>>()
    };
    ($($t:ty),*; $n:expr) => {
        (0..$n).map(|_|
                    get!($($t),*)
        ).collect::<Vec<_>>()
    };
    ($t:ty |) => {
        {
            let mut line: String = String::new();
            std::io::stdin().read_line(&mut line).unwrap();
            line.split_whitespace()
                .map(|t| t.parse::<$t>().unwrap())
                .collect::<Vec<_>>()
        }
    };
    ($t:ty | $n:expr) => {
        (0..$n).map(|_| get!($t |)).collect::<Vec<_>>()
    };
}

macro_rules! tern {
    ($condition: expr, $_true: expr, $_false: expr) => {
        if $condition {
            $_true
        } else {
            $_false
        }
    };
}

use std::collections::VecDeque;

fn get_t_consumption_for_one_s(s: &[char], t_partial: &[char], mut map: Vec<VecDeque<usize>>) -> (usize, u64) {
    let mut s_count = 0;
    let mut t_count = 0;
    for &tc in t_partial {
        let mut found = false;
        while let Some(map_i) = map[tc as usize].pop_front() {
            if map_i < s_count {
                continue
            }
            s_count = map_i + 1;
            found = true;
            break;
        }
        if !found {
            break;
        }
        t_count += 1;
    }
    return (t_count, s_count as u64);
}

fn main() {
    let s = get!(String).chars().collect::<Vec<_>>();
    let t = get!(String).chars().collect::<Vec<_>>();
    let mut map = vec![VecDeque::new(); 'z' as usize + 1];
    for (i, &sc) in s.iter().enumerate() {
        map[sc as usize].push_back(i);
    }
    let mut s_count = 0u64;
    let mut t_start = 0;
    let t_len = t.len();
    loop {
        let (t_consump, s_consump) = get_t_consumption_for_one_s(&s, &t[t_start..t_len], map.clone());
        if t_consump == 0 {
            println!("-1");
            return;
        }
        t_start += t_consump;
        if t_start == t_len {
            s_count += s_consump;
            break;
        }
        s_count += s.len() as u64;
    }
    println!("{}", s_count);
}