Problem:
Score: 500 points

Problem Statement

Takahashi will take part in an eating contest. Teams of N members will compete in this contest, and Takahashi's team consists of N players numbered 1 through N from youngest to oldest. The consumption coefficient of Member i is A_i.

In the contest, N foods numbered 1 through N will be presented, and the difficulty of Food i is F_i. The details of the contest are as follows:

A team should assign one member to each food, and should not assign the same member to multiple foods.

It will take x \times y seconds for a member to finish the food, where x is the consumption coefficient of the member and y is the difficulty of the dish.

The score of a team is the longest time it takes for an individual member to finish the food.

Before the contest, Takahashi's team decided to do some training. In one set of training, a member can reduce his/her consumption coefficient by 1, as long as it does not go below 0. However, for financial reasons, the N members can do at most K sets of training in total.

What is the minimum possible score of the team, achieved by choosing the amounts of members' training and allocating the dishes optimally?

Constraints

All values in input are integers.

1 \leq N \leq 2 \times 10^5

0 \leq K \leq 10^{18}

1 \leq A_i \leq 10^6\ (1 \leq i \leq N)

1 \leq F_i \leq 10^6\ (1 \leq i \leq N)

Input

Input is given from Standard Input in the following format:

N K
A_1 A_2 ... A_N
F_1 F_2 ... F_N

Output

Print the minimum possible score of the team.

Sample Input 1

3 5
4 2 1
2 3 1

Sample Output 1

2

They can achieve the score of 2, as follows:

Member 1 does 4 sets of training and eats Food 2 in (4-4) \times 3 = 0 seconds.

Member 2 does 1 set of training and eats Food 3 in (2-1) \times 1 = 1 second.

Member 3 does 0 sets of training and eats Food 1 in (1-0) \times 2 = 2 seconds.

They cannot achieve a score of less than 2, so the answer is 2.

Sample Input 2

3 8
4 2 1
2 3 1

Sample Output 2

0

They can choose not to do exactly K sets of training.

Sample Input 3

11 14
3 1 4 1 5 9 2 6 5 3 5
8 9 7 9 3 2 3 8 4 6 2

Sample Output 3

12

Solution in Rust (1.15.1) (judge verdict: Accepted)

// SNIPPET read
pub trait Readable {
    type Output;
    fn words_count() -> usize;
    fn read_words(words: &[&str]) -> Result<Self::Output, String>;
}
#[macro_export]
macro_rules! readable {
    ( $t:ty, $words_count:expr, |$words:ident| $read_words:expr ) => {
        impl Readable for $t {
            type Output = $t;
            fn words_count() -> usize { $words_count }
            fn read_words($words: &[&str]) -> Result<$t, String> {
                Ok($read_words)
            }
        }
    };
}
readable!((), 1, |_ss| ());
readable!(String, 1, |ss| ss[0].to_string());
impl Readable for char {
    type Output = char;
    fn words_count() -> usize { 1 }
    fn read_words(words: &[&str]) -> Result<char, String> {
        let chars: Vec<char> = words[0].chars().collect();
        if chars.len() == 1 {
            Ok(chars[0])
        } else {
            Err(format!("cannot parse `{}` as a char", words[0]))
        }
    }
}
pub struct Chars();
impl Readable for Chars {
    type Output = Vec<char>;
    fn words_count() -> usize { 1 }
    fn read_words(words: &[&str]) -> Result<Vec<char>, String> {
        Ok(words[0].chars().collect())
    }
}
macro_rules! impl_readable_for_ints {
    ( $( $t:ty )* ) => { $(
        impl Readable for $t {
            type Output = Self;
            fn words_count() -> usize { 1 }
            fn read_words(words: &[&str]) -> Result<$t, String> {
                use std::str::FromStr;
                <$t>::from_str(words[0]).map_err(|_| {
                    format!("cannot parse `{}` as {}", words[0], stringify!($t))
                })
            }
        }
    )* };
}
impl_readable_for_ints!(i8 u8 i16 u16 i32 u32 i64 u64 isize usize f32 f64);
macro_rules! define_one_origin_int_types {
    ( $new_t:ident $int_t:ty ) => {
        #[allow(non_camel_case_types)]
        pub struct $new_t;
        impl Readable for $new_t {
            type Output = $int_t;
            fn words_count() -> usize { 1 }
            fn read_words(words: &[&str]) -> Result<Self::Output, String> {
                <$int_t>::read_words(words).map(|n| n-1)
            }
        }
    };
    ( $new_t:ident $int_t:ty; $( $inner_new_t:ident $inner_int_t:ty );* ) => {
        define_one_origin_int_types!($new_t $int_t);
        define_one_origin_int_types!($($inner_new_t $inner_int_t);*);
    };
}
define_one_origin_int_types!(u8_ u8; u16_ u16; u32_ u32; u64_ u64; usize_ usize);
macro_rules! impl_readable_for_tuples {
    ( $t:ident $var:ident ) => ();
    ( $t:ident $var:ident; $( $inner_t:ident $inner_var:ident );* ) => {
        impl_readable_for_tuples!($($inner_t $inner_var);*);
        impl<$t: Readable, $($inner_t: Readable),*> Readable
            for ($t, $($inner_t),*)
        {
            type Output = ( <$t>::Output, $(<$inner_t>::Output),* );
            fn words_count() -> usize {
                let mut n = <$t>::words_count();
                $(
                    n += <$inner_t>::words_count();
                )*
                n
            }
            #[allow(unused_assignments)]
            fn read_words(words: &[&str]) ->
                Result<Self::Output, String>
            {
                let mut start = 0;
                let $var = <$t>::read_words(
                    &words[start .. start+<$t>::words_count()]
                )?;
                start += <$t>::words_count();
                $(
                    let $inner_var =
                        <$inner_t>::read_words(
                            &words[start .. start+<$inner_t>::words_count()]
                        )?;
                    start += <$inner_t>::words_count();
                )*
                Ok(( $var, $($inner_var),* ))
            }
        }
    };
}
impl_readable_for_tuples!(T8 x8; T7 x7; T6 x6; T5 x5; T4 x4; T3 x3; T2 x2; T1 x1);
pub trait ReadableFromLine {
    type Output;
    fn read_line(line: &str) -> Result<Self::Output, String>;
}
fn split_into_words(line: &str) -> Vec<&str> {
    #[allow(deprecated)]
    line.trim_right_matches('\n').split_whitespace().collect()
}
impl<T: Readable> ReadableFromLine for T {
    type Output = T::Output;
    fn read_line(line: &str) -> Result<T::Output, String> {
        let words = split_into_words(line);
        if words.len() != T::words_count() {
            return Err(format!("line `{}` has {} words, expected {}",
                               line, words.len(), T::words_count()));
        }
        T::read_words(&words)
    }
}
macro_rules! impl_readable_from_line_for_tuples_with_from_iterator {
    ( $u:ident : $( + $bound:path )* => $seq_in:ty, $seq_out:ty; $t:ident $var:ident ) => {
        impl<$u: Readable> ReadableFromLine for $seq_in
        where
            <$u as Readable>::Output: Sized $(+ $bound)*
        {
            type Output = $seq_out;
            fn read_line(line: &str) -> Result<$seq_out, String> {
                let n = $u::words_count();
                let words = split_into_words(line);
                if words.len() % n != 0 {
                    return Err(format!("line `{}` has {} words, expected multiple of {}",
                                       line, words.len(), n));
                }
                let mut result = Vec::new();
                for chunk in words.chunks(n) {
                    match $u::read_words(chunk) {
                        Ok(v) => result.push(v),
                        Err(msg) => {
                            let flagment_msg = if n == 1 {
                                format!("word {}", result.len())
                            } else {
                                let l = result.len();
                                format!("words {}-{}", n*l + 1, (n+1) * l)
                            };
                            return Err(format!(
                                "{} of line `{}`: {}", flagment_msg, line, msg
                            ));
                        }
                    }
                }
                Ok(result.into_iter().collect())
            }
        }
        impl<T: Readable, $u: Readable> ReadableFromLine for (T, $seq_in)
        where
            <$u as Readable>::Output: Sized $(+ $bound)*
        {
            type Output = (T::Output, $seq_out);
            fn read_line(line: &str) -> Result<Self::Output, String> {
                let n = T::words_count();
                #[allow(deprecated)]
                let trimmed = line.trim_right_matches('\n');
                let words_and_rest: Vec<&str> = trimmed.splitn(n + 1, ' ').collect();
                if words_and_rest.len() < n {
                    return Err(format!("line `{}` has {} words, expected at least {}",
                                       line, words_and_rest.len(), n));
                }
                let words = &words_and_rest[..n];
                let empty_str = "";
                let rest = words_and_rest.get(n).unwrap_or(&empty_str);
                Ok((T::read_words(words)?, <$seq_in>::read_line(rest)?))
            }
        }
    };
    ( $u:ident : $( + $bound:path )* => $seq_in:ty, $seq_out:ty;
      $t:ident $var:ident, $( $inner_t:ident $inner_var:ident ),+ ) => {
        impl_readable_from_line_for_tuples_with_from_iterator!(
            $u: $(+ $bound)* => $seq_in, $seq_out; $($inner_t $inner_var),+
        );
        impl<$t: Readable, $($inner_t: Readable),+ , $u: Readable> ReadableFromLine
            for ($t, $($inner_t),+ , $seq_in)
        where
            <$u as Readable>::Output: Sized $(+ $bound)*
        {
            type Output = ($t::Output, $($inner_t::Output),+ , $seq_out);
            fn read_line(line: &str) -> Result<Self::Output, String> {
                let mut n = $t::words_count();
                $(
                    n += $inner_t::words_count();
                )+
                #[allow(deprecated)]
                let trimmed = line.trim_right_matches('\n');
                let words_and_rest: Vec<&str> = trimmed.splitn(n + 1, ' ')
                    .collect();
                if words_and_rest.len() < n {
                    return Err(
                        format!("line `{}` has {} words, expected at least {}",
                                line, words_and_rest.len(), n)
                    );
                }
                let words = &words_and_rest[..n];
                let empty_str = "";
                let rest = words_and_rest.get(n).unwrap_or(&empty_str);
                let ($var, $($inner_var),*) =
                    <($t, $($inner_t),+)>::read_words(words)?;
                Ok(($var, $($inner_var),* , <$seq_in>::read_line(rest)?))
            }
        }
    };
}
#[macro_export]
macro_rules! readable_collection {
    ($u:ident => $collection_in:ty, $collection_out:ty) => {
        impl_readable_from_line_for_tuples_with_from_iterator!(
            $u: => $collection_in, $collection_out;
            T8 x8, T7 x7, T6 x6, T5 x5, T4 x4, T3 x3, T2 x2, T1 x1
        );
    };
    ($u:ident : $( $bound:path ),* => $collection_in:ty, $collection_out:ty) => {
        impl_readable_from_line_for_tuples_with_from_iterator!(
            $u: $(+ $bound)* => $collection_in, $collection_out;
            T8 x8, T7 x7, T6 x6, T5 x5, T4 x4, T3 x3, T2 x2, T1 x1
        );
    }
}
readable_collection!(U => Vec<U>, Vec<U::Output>);
readable_collection!(
    U => std::collections::VecDeque<U>, std::collections::VecDeque<U::Output>
);
readable_collection!(
    U: Eq, std::hash::Hash => std::collections::HashSet<U>, std::collections::HashSet<U::Output>
);
readable_collection!(
    U: Ord => std::collections::BTreeSet<U>, std::collections::BTreeSet<U::Output>
);
readable_collection!(
    U: Ord => std::collections::BinaryHeap<U>, std::collections::BinaryHeap<U::Output>
);
pub fn read<T: ReadableFromLine>() -> T::Output {
    let mut line = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    T::read_line(&line).unwrap()
}
#[macro_export]
macro_rules! read {
    () => {
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).unwrap();
    };
    ( $pat:pat = $t:ty ) => {
        let $pat = read::<$t>();
    };
    ( $( $pat:pat = $t:ty ),+ ) => {
        read!(($($pat),*) = ($($t),*));
    };
}
#[macro_export]
macro_rules! readls {
    ( $( $pat:pat = $t:ty ),+ ) => {
        $(
            read!($pat = $t);
        )*
    };
}
pub fn readx<T: ReadableFromLine>() -> Vec<T::Output> {
    use std::io::{self, BufRead};
    let stdin = io::stdin();
    let result = stdin.lock().lines().map(|line_result| {
        let line = line_result.expect("read from stdin failed");
        T::read_line(&line).unwrap()
    }).collect();
    result
}
#[macro_export]
macro_rules! readx_loop {
    ( |$pat:pat = $t:ty| $body:expr ) => {
        {
            use std::io::BufRead;
            let stdin = std::io::stdin();
            for line in stdin.lock().lines() {
                let line = line.expect("read from stdin failed");
                let $pat = <$t>::read_line(&line).unwrap();
                $body
            }
        }
    };
    ( |$($pat:pat = $t:ty),*| $body:expr ) => {
        readx_loop!(|($($pat),*) = ($($t),*)| $body);
    };
}
pub fn readn<T: ReadableFromLine>(n: usize) -> Vec<T::Output> {
    use std::io::{self, BufRead};
    let stdin = io::stdin();
    let result: Vec<T::Output> = stdin.lock().lines().take(n).map(|line_result| {
        let line = line_result.expect("read from stdin failed");
        T::read_line(&line).unwrap()
    }).collect();
    if result.len() < n {
        panic!("expected reading {} lines, but only {} lines are read",
               n, result.len());
    }
    result
}
#[macro_export]
macro_rules! readn_loop {
    ( $n:expr, |$pat:pat = $t:ty| $body:expr ) => {
        {
            use std::io::BufRead;
            let stdin = std::io::stdin();
            let mut lock = stdin.lock();
            for _ in 0..$n {
                let mut line = String::new();
                lock.read_line(&mut line).expect("read from stdin failed");
                let $pat = <$t>::read_line(&line).unwrap();
                $body
            }
        }
    };
    ( $n:expr, |$($pat:pat = $t:ty),*| $body:expr ) => {
        readn_loop!($n, |($($pat),*) = ($($t),*)| $body);
    };
}
pub trait Words {
    fn read<T: Readable>(&self) -> T::Output;
}
impl<'a> Words for [&'a str] {
    fn read<T: Readable>(&self) -> T::Output {
        T::read_words(self).unwrap()
    }
}
impl<'a> Words for &'a str {
    fn read<T: Readable>(&self) -> T::Output {
        T::read_words(&[self]).unwrap()
    }
}
// SNIPPET cmp
use std::cmp::{Ord, Ordering};
#[derive(Clone, Copy, PartialEq, Eq, Debug, Default, Hash)]
pub struct Reverse<T: Ord>(pub T);
impl<T: Ord> PartialOrd for Reverse<T> {
    fn partial_cmp(&self, other: &Reverse<T>) -> Option<Ordering> {
        other.0.partial_cmp(&self.0)
    }
}
impl<T: Ord> Ord for Reverse<T> {
    fn cmp(&self, other: &Reverse<T>) -> Ordering {
        other.0.cmp(&self.0)
    }
}
pub trait SortDesc<T> {
    fn sort_desc(&mut self) where T: Ord;
    fn sort_desc_by_key<K: Ord, F: FnMut(&T) -> K>(&mut self, f: F);
}
impl<T> SortDesc<T> for [T] {
    fn sort_desc(&mut self) where T: Ord {
        self.sort();
        self.reverse();
    }
    fn sort_desc_by_key<K: Ord, F: FnMut(&T) -> K>(&mut self, mut f: F) {
        self.sort_by_key(|x| Reverse(f(x)));
    }
}
#[derive(Clone, Copy, PartialEq, PartialOrd, Debug, Default, Hash)]
pub struct Total<T: PartialOrd + PartialEq>(pub T);
impl<T: PartialOrd + PartialEq> Eq for Total<T> {}
impl<T: PartialOrd + PartialEq> Ord for Total<T> {
    fn cmp(&self, other: &Self) -> Ordering {
        self.partial_cmp(other).unwrap()
    }
}
// SNIPPET num
pub trait PrimitiveInteger:
    Sized + Ord +
    std::ops::Add<Output=Self> +
    std::ops::Sub<Output=Self> +
    std::ops::Div<Output=Self>
{
    fn one() -> Self;
    fn abs_diff(self, rhs: Self) -> Self;
    fn rem_euclid(self, rhs: Self) -> Self;
}
macro_rules! impl_primitive_integer {
    ( $($t: ty)* ) => { $(
        impl PrimitiveInteger for $t {
            fn one() -> $t {
                1
            }
            fn abs_diff(self, rhs: $t) -> $t {
                if self < rhs { rhs - self } else { self - rhs }
            }
            #[allow(unused_comparisons)]
            fn rem_euclid(self, rhs: $t) -> $t {
                let r = self % rhs;
                if r < 0 {
                    if rhs < 0 { r - rhs } else { r + rhs }
                } else {
                    r
                }
            }
        }
    )* }
}
impl_primitive_integer!(u8 u16 u32 u64 usize i8 i16 i32 i64 isize);
pub trait PrimitiveUnsigned: PrimitiveInteger {
    fn ceil_div(self, rhs: Self) -> Self;
    fn round_div(self, rhs: Self) -> Self;
    fn log2(self) -> Option<Self>;
    fn ceil_log2(self) -> Option<Self>;
    fn sqrt(self) -> Self;
}
macro_rules! impl_primitive_unsigned {
    ( $($t: ty)* ) => { $(
        impl PrimitiveUnsigned for $t {
            fn ceil_div(self, rhs: $t) -> $t {
                (self + rhs - 1) / rhs
            }
            fn round_div(self, rhs: $t) -> $t {
                (self + rhs/2) / rhs
            }
            fn log2(mut self) -> Option<$t> {
                if self == 0 {
                    None
                } else {
                    let mut ans = 0;
                    while self > 1 {
                        ans += 1;
                        self /= 2;
                    }
                    Some(ans)
                }
            }
            fn ceil_log2(self) -> Option<$t> {
                self.log2().map(|x| {
                    (self + ((1<<x) - 1)).log2().unwrap()
                })
            }
            fn sqrt(self) -> $t {
                (self as f64).sqrt() as $t
            }
        }
    )* }
}
impl_primitive_unsigned!(u8 u16 u32 u64 usize);
pub fn gcd(a: u64, b: u64) -> u64 {
    if b == 0 { a } else { gcd(b, a%b) }
}
pub fn bezout(a: i64, b: i64) -> (i64, i64, u64) {
    let (x, y, g) = bezout_sub((a * a.signum()) as u64, (b * b.signum()) as u64);
    (x * a.signum(), y * b.signum(), g)
}
fn bezout_sub(a: u64, b: u64) -> (i64, i64, u64) {
    if b == 0 { (1, 0, a) } else {
        let m = (a / b) as i64;
        let (x, y, g) = bezout_sub(b, a%b);
        (y, x - m*y, g)
    }
}
macro_rules! forward_ref_unop {
    (impl $op:ident, $method:ident for $t:ty) => {
        impl std::ops::$op for &$t {
            type Output = <$t as std::ops::$op>::Output;
            fn $method(self) -> <$t as std::ops::$op>::Output {
                std::ops::$op::$method(*self)
            }
        }
    }
}
macro_rules! forward_ref_binop {
    (impl $op:ident, $method:ident for $t:ty, $u:ty) => {
        impl<'a> std::ops::$op<$u> for &'a $t {
            type Output = <$t as std::ops::$op<$u>>::Output;
            fn $method(self, other: $u) -> <$t as std::ops::$op<$u>>::Output {
                std::ops::$op::$method(*self, other)
            }
        }
        impl std::ops::$op<&$u> for $t {
            type Output = <$t as std::ops::$op<$u>>::Output;
            fn $method(self, other: &$u) -> <$t as std::ops::$op<$u>>::Output {
                std::ops::$op::$method(self, *other)
            }
        }
        impl std::ops::$op<&$u> for &$t {
            type Output = <$t as std::ops::$op<$u>>::Output;
            fn $method(self, other: &$u) -> <$t as std::ops::$op<$u>>::Output {
                std::ops::$op::$method(*self, *other)
            }
        }
    }
}
macro_rules! forward_ref_op_assign {
    (impl $op:ident, $method:ident for $t:ty, $u:ty) => {
        impl std::ops::$op<&$u> for $t {
            fn $method(&mut self, other: &$u) {
                std::ops::$op::$method(self, *other);
            }
        }
    }
}
// SNIPPET bsearch
pub trait BSearch: Sized {
    type Item;
    fn is_empty(&self) -> bool;
    fn leftmost_item(&self) -> Self::Item;
    fn rightmost_item(&self) -> Self::Item;
    fn middle_item(&self) -> Self::Item;
    fn left_half(&self) -> Self;
    fn right_half(&self) -> Self;
    fn is_bsearch_converged(&self) -> bool;
    fn bsearch_left_max<F>(&self, mut is_left: F) -> Option<Self::Item>
    where
        F: FnMut(&Self::Item) -> bool
    {
        if self.is_empty() {
            None
        } else if !is_left(&self.leftmost_item()) {
            None
        } else {
            let rightmost = self.rightmost_item();
            if is_left(&rightmost) {
                Some(rightmost)
            } else {
                Some(bsearch_left_max_sub(self, is_left))
            }
        }
    }
    fn bsearch_right_min<F>(&self, mut is_right: F) -> Option<Self::Item>
    where
        F: FnMut(&Self::Item) -> bool
    {
        if self.is_empty() {
            None
        } else if !is_right(&self.rightmost_item()) {
            None
        } else {
            let leftmost = self.leftmost_item();
            if is_right(&leftmost) {
                Some(leftmost)
            } else {
                Some(bsearch_right_min_sub(self, is_right))
            }
        }
    }
}
fn bsearch_left_max_sub<Items, T, F>(items: &Items, mut is_left: F) -> T
where
    Items: BSearch<Item=T>,
    F: FnMut(&T) -> bool
{
    if items.is_bsearch_converged() {
        items.leftmost_item()
    } else {
        if is_left(&items.middle_item()) {
            bsearch_left_max_sub(&items.right_half(), is_left)
        } else {
            bsearch_left_max_sub(&items.left_half(), is_left)
        }
    }
}
fn bsearch_right_min_sub<Items, T, F>(items: &Items, mut is_right: F) -> T
where
    Items: BSearch<Item=T>,
    F: FnMut(&T) -> bool
{
    if items.is_bsearch_converged() {
        items.rightmost_item()
    } else {
        if is_right(&items.middle_item()) {
            bsearch_right_min_sub(&items.left_half(), is_right)
        } else {
            bsearch_right_min_sub(&items.right_half(), is_right)
        }
    }
}
impl<T: PrimitiveInteger + Clone> BSearch for std::ops::Range<T> {
    type Item = T;
    fn is_empty(&self) -> bool {
        self.end <= self.start
    }
    fn leftmost_item(&self) -> T {
        self.start.clone()
    }
    fn rightmost_item(&self) -> T {
        self.end.clone() - T::one()
    }
    fn middle_item(&self) -> T {
        (self.start.clone() + self.end.clone()) / (T::one() + T::one())
    }
    fn left_half(&self) -> std::ops::Range<T> {
        self.start.clone()..(self.middle_item() + T::one())
    }
    fn right_half(&self) -> std::ops::Range<T> {
        self.middle_item()..self.end.clone()
    }
    fn is_bsearch_converged(&self) -> bool {
        BSearch::is_empty(self) || self.end.clone() - self.start.clone() <= T::one() + T::one()
    }
}
impl<'a, T> BSearch for &'a [T] {
    type Item = &'a T;
    fn is_empty(&self) -> bool {
        <[T]>::is_empty(self)
    }
    fn leftmost_item(&self) -> &'a T {
        self.first().unwrap()
    }
    fn rightmost_item(&self) -> &'a T {
        self.last().unwrap()
    }
    fn middle_item(&self) -> &'a T {
        self.get(self.len() / 2).unwrap()
    }
    fn left_half(&self) -> &'a [T] {
        &self[..(self.len() / 2 + 1)]
    }
    fn right_half(&self) -> &'a [T] {
        &self[(self.len() / 2)..]
    }
    fn is_bsearch_converged(&self) -> bool {
        self.len() <= 2
    }
}
pub trait SliceBSearch {
    type Item;
    fn bsearch_left_max<F>(&self, is_left: F) -> Option<&Self::Item>
    where
        F: FnMut(&Self::Item) -> bool;
    fn bsearch_index_left_max<F>(&self, is_left: F) -> Option<usize>
    where
        F: FnMut(&Self::Item) -> bool;
    fn bsearch_right_min<F>(&self, is_right: F) -> Option<&Self::Item>
    where
        F: FnMut(&Self::Item) -> bool;
    fn bsearch_index_right_min<F>(&self, is_right: F) -> Option<usize>
    where
        F: FnMut(&Self::Item) -> bool;
}
impl<T> SliceBSearch for [T] {
    type Item = T;
    fn bsearch_left_max<F>(&self, mut is_left: F) -> Option<&T>
    where
        F: FnMut(&T) -> bool
    {
        BSearch::bsearch_left_max(&self, |&x| is_left(x))
    }
    fn bsearch_index_left_max<F>(&self, mut is_left: F) -> Option<usize>
    where
        F: FnMut(&T) -> bool
    {
        (0..self.len()).bsearch_left_max(|&i| {
            let x = unsafe { self.get_unchecked(i) };
            is_left(x)
        })
    }
    fn bsearch_right_min<F>(&self, mut is_right: F) -> Option<&T>
    where
        F: FnMut(&T) -> bool
    {
        BSearch::bsearch_right_min(&self, |&x| is_right(x))
    }
    fn bsearch_index_right_min<F>(&self, mut is_right: F) -> Option<usize>
    where
        F: FnMut(&T) -> bool
    {
        (0..self.len()).bsearch_right_min(|&i| {
            let x = unsafe { self.get_unchecked(i) };
            is_right(x)
        })
    }
}
// END SNIPPETS

fn main() {
    read!(_ = (), k = u64);
    read!(mut aa = Vec<u64>);
    aa.sort();
    read!(mut fs = Vec<u64>);
    fs.sort_desc();
    let ans = (0..1_000_000_000_000_000_000u64).bsearch_right_min(|&x| {
        let max_as = fs.iter().map(|f| x/f);
        let s: u64 = aa.iter().zip(max_as).map(|(a, max_a)| a.saturating_sub(max_a)).sum();
        k >= s
    }).unwrap();
    println!("{}", ans);
}