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)

// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[allow(unused_macros)]
macro_rules! p {
    ($($x:expr),*) => {
        $(println!("{:?}", $x);)*
    };
}
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        #[allow(unused_mut)]
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };

    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
#[allow(unused_imports)]
use std::cmp::*;
trait Each: Iterator {
    fn each<F>(self, mut f: F)
    where
        Self: Sized,
        F: FnMut(Self::Item),
    {
        self.fold((), move |(), item| f(item));
    }
}
impl<T: Iterator> Each for T {}

fn main() {
    input! {
        s:chars,
        t:chars,
    }
    let mut s = s
        .into_iter()
        .map(|x| x as u8 as usize - 97)
        .collect::<Vec<_>>();
    let mut s_ = s.clone();
    s.append(&mut s_);
    //dbg!(&s);
    let t = t
        .into_iter()
        .map(|x| x as u8 as usize - 97)
        .collect::<Vec<_>>();
    let (sl, tl) = (s.len(), t.len());
    let mut az = vec![vec![-1; sl]; 26];
    for (i, &x) in s.iter().enumerate() {
        az[x][i] = 1;
    }
    for x in 0..26 {
        let mut tmp = 1;
        let mut flag = false;
        for i in (0..sl).rev() {
            if az[x][i] == 1 {
                tmp = 1;
                flag = true;
            } else if flag {
                tmp += 1;
                az[x][i] = tmp;
            }
        }
    }
    let mut ans: i64 = 1;
    let mut n: usize = 0;
    for &x in &t {
        if az[x][n] == -1 {
            ans = -1;
            break;
        } else {
            ans += az[x][n] - 1;
            n = (n + az[x][n] as usize - 1) % (sl / 2);
        }
    }
    //dbg!(&az);
    p!(ans);
}