#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

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

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

#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

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

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

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

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*);
    }
}

#[allow(unused_imports)]
use std::cmp::{min, max};
#[allow(unused_imports)]
use std::io::{stdout, stdin, BufWriter, Write};

pub fn lower_bound<T: Ord>(a: &Vec<T>, x: &T) -> usize {
    use std::cmp::Ordering;
    let mut l = 0;
    let mut r = a.len();
    while l != r {
        let m = l + (r - l) / 2;
        match a[m].cmp(x) {
            Ordering::Less => l = m + 1,
            Ordering::Equal | Ordering::Greater => r = m,
        }
    }
    l
}

fn main() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }

    input!{
      s: chars,
      t: chars,
    }

    let n = s.len();
    let mut indexes = vec![vec![]; 28];
    for i in 0..n {
        let c = s[i];
        let idx = (c as u8 - 'a' as u8) as usize;
        indexes[idx].push(i);
    }

    let mut cur = 0;
    for c in t {
        let idx = (c as u8 - 'a' as u8) as usize;
        if indexes[idx].len() == 0 {
            return puts!("{}\n", -1);
        }
        let cur_index = cur%n;
        let found = lower_bound(&indexes[idx], &cur_index);
        let found_index = if found == indexes[idx].len() {
            n + indexes[idx][0]
        } else {
            indexes[idx][found]
        };
        // debug!(idx, cur_index, found_index, indexes[idx]);

        cur = found_index + cur/n*n + 1;
        // debug!(c, cur);
    }
    puts!("{}\n", cur);
}


Measured memory_bytes: 6396