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 mut s_buff = String::new();
    std::io::stdin().read_line(&mut s_buff).ok();
    let vec_str: Vec<String> = s_buff.trim().split_whitespace().map(|x| x.to_string()).collect();
    let s = vec_str[0].parse::<String>().unwrap();
    let s: Vec<char> = s.chars().collect();

    let mut s_buff = String::new();
    std::io::stdin().read_line(&mut s_buff).ok();
    let vec_str: Vec<String> = s_buff.trim().split_whitespace().map(|x| x.to_string()).collect();
    let t = vec_str[0].parse::<String>().unwrap();
    let t: Vec<char> = t.chars().collect();

    // Check answer existense
    let mut flag = false;

    for t_cnt in 0..t.len() {
        for s_cnt in 0..s.len() {
            if s[s_cnt] == t[t_cnt] {
                flag = true;
                break;
            }
        }

        if flag {
            continue;
        } else {
            println!("{:?}", -1);
            return;
        }
    }

    // Answer exists
    let mut count = 0;
    let mut pos = 0;
    for t_cnt in 0..t.len() {
        loop {
            flag = false;
            for s_cnt in pos..s.len() {
                if s[s_cnt] == t[t_cnt] {
                    pos = s_cnt;
                    flag = true;

                    if t_cnt == t.len()-1 {
                        println!("{:?}", count * s.len() + pos + 1);
                        return;
                    }
                    break;
                }
            }
            
            if flag {
                break;
            } else {
                pos = 0;
                count = count + 1;
            }
        }
    }
}