#![allow(non_snake_case, unused_imports, unused_must_use)]
use std::io::{self, prelude::*};
use std::str;

fn main() {
    let (stdin, stdout) = (io::stdin(), io::stdout());
    let mut scan = Scanner::new(stdin.lock());
    let mut out = io::BufWriter::new(stdout.lock());

    macro_rules! input {
        ($T: ty) => {
            scan.token::<$T>()
        };
        ($T: ty, $N: expr) => {
            (0..$N).map(|_| scan.token::<$T>()).collect::<Vec<_>>()
        };
    }

    let N = input!(usize);
    let H = input!(isize);
    let A = input!(isize, N);
    let B = input!(isize, N);

    let mut BIT_A = BinaryIndexedTree::new(N);
    let mut BIT_B = BinaryIndexedTree::new(N);

    for i in 0..N {
        BIT_A.add(i, A[i]);
        BIT_B.add(i, B[i]);
    }

    let mut ans = 0;
    let mut right = 0;
    let mut h_now = 0;

    for left in 0..N {
        loop {
            if right < N {
                h_now += B[right] * (right + 1 - left) as isize;
                right += 1;
            } else {
                break;
            }

            if h_now > H {
                right -= 1;
                h_now -= B[right] * (right + 1 - left) as isize;
                break;
            }
        }

        if left < right {
            ans = std::cmp::max(ans, BIT_A.sum(left..right));
            h_now -= BIT_B.sum(left..right);
        }
    }

    writeln!(out, "{}", ans);
}

pub struct BinaryIndexedTree<T> {
    tree: Vec<T>,
}

impl<T: Default + Clone + Copy + std::ops::AddAssign + std::ops::Sub<Output = T>>
    BinaryIndexedTree<T>
{
    /// self = [0; size]
    pub fn new(size: usize) -> Self {
        return Self {
            tree: vec![T::default(); size + 1],
        };
    }

    /// self[i] <- self[i] + w
    pub fn add(&mut self, i: usize, w: T) {
        self._inner_add(i + 1, w);
    }

    /// return Σ_{j ∈ [0, i]} self[j]
    pub fn prefix_sum(&self, i: usize) -> T {
        self._inner_sum(i + 1)
    }

    /// return Σ_{j ∈ range} self[j]
    pub fn sum<R: std::ops::RangeBounds<usize>>(&self, range: R) -> T {
        let left = match range.start_bound() {
            std::ops::Bound::Included(&l) => l,
            std::ops::Bound::Excluded(&l) => l + 1,
            std::ops::Bound::Unbounded => 0,
        };

        let right = match range.end_bound() {
            std::ops::Bound::Included(&r) => r,
            std::ops::Bound::Excluded(&r) => r - 1,
            std::ops::Bound::Unbounded => self.tree.len() - 2,
        };

        if left == 0 {
            return self.prefix_sum(right);
        } else {
            return self.prefix_sum(right) - self.prefix_sum(left - 1);
        }
    }

    fn _inner_add(&mut self, mut i: usize, w: T) {
        while i < self.tree.len() {
            self.tree[i] += w;
            i += i & i.wrapping_neg();
        }
    }

    fn _inner_sum(&self, mut i: usize) -> T {
        let mut ret = T::default();
        while i > 0 {
            ret += self.tree[i];
            i -= i & i.wrapping_neg();
        }
        return ret;
    }
}

struct Scanner<R> {
    reader: R,
    buf_str: Vec<u8>,
    buf_iter: str::SplitWhitespace<'static>,
}
impl<R: BufRead> Scanner<R> {
    fn new(reader: R) -> Self {
        Self {
            reader,
            buf_str: vec![],
            buf_iter: "".split_whitespace(),
        }
    }
    fn token<T: str::FromStr>(&mut self) -> T {
        loop {
            if let Some(token) = self.buf_iter.next() {
                return token.parse().ok().expect("Failed parse");
            }
            self.buf_str.clear();
            self.reader
                .read_until(b'\n', &mut self.buf_str)
                .expect("Failed read");
            self.buf_iter = unsafe {
                let slice = str::from_utf8_unchecked(&self.buf_str);
                std::mem::transmute(slice.split_whitespace())
            }
        }
    }
}