Problem:
Score : 600 points

Problem Statement

We have a grid with A horizontal rows and B vertical columns, with the squares painted white. On this grid, we will repeatedly apply the following operation:

Assume that the grid currently has a horizontal rows and b vertical columns. Choose "vertical" or "horizontal".

If we choose "vertical", insert one row at the top of the grid, resulting in an (a+1) \times b grid.

If we choose "horizontal", insert one column at the right end of the grid, resulting in an a \times (b+1) grid.

Then, paint one of the added squares black, and the other squares white.

Assume the grid eventually has C horizontal rows and D vertical columns. Find the number of ways in which the squares can be painted in the end, modulo 998244353.

Constraints

1 \leq A \leq C \leq 3000

1 \leq B \leq D \leq 3000

A, B, C, and D are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of ways in which the squares can be painted in the end, modulo 998244353.

Sample Input 1

1 1 2 2

Sample Output 1

3

Any two of the three squares other than the bottom-left square can be painted black.

Sample Input 2

2 1 3 4

Sample Output 2

65

Sample Input 3

31 41 59 265

Sample Output 3

387222020

Solution in Rust (1.42.0) (judge verdict: Accepted)

#[macro_export]
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 <_ >>() } ;($iter :expr ,{$t :tt =>$f :expr } ) =>{$f (read_value !($iter ,$t ) ) } ;($iter :expr ,chars ) =>{read_value !($iter ,String ) .chars () .collect ::<Vec <char >>() } ;($iter :expr ,usize1 ) =>{read_value !($iter ,usize ) -1 } ;($iter :expr ,$t :ty ) =>{$iter .next () .unwrap () .parse ::<$t >() .unwrap () } ;}
#[macro_export]
macro_rules !input_inner {($iter :expr ) =>{} ;($iter :expr ,) =>{} ;($iter :expr ,mut $var :ident :$t :tt $($r :tt ) *) =>{let mut $var =read_value !($iter ,$t ) ;input_inner !{$iter $($r ) *} } ;($iter :expr ,mut $var :ident $($r :tt ) *) =>{input_inner !{$iter ,mut $var :usize $($r ) *} } ;($iter :expr ,$var :ident :$t :tt $($r :tt ) *) =>{let $var =read_value !($iter ,$t ) ;input_inner !{$iter $($r ) *} } ;($iter :expr ,$var :ident $($r :tt ) *) =>{input_inner !{$iter ,$var :usize $($r ) *} } ;}
#[macro_export]
macro_rules !input {(source =$s :expr ,$($r :tt ) *) =>{let mut iter =$s .split_whitespace () ;input_inner !{iter ,$($r ) *} } ;(iter =$iter :ident ,$($r :tt ) *) =>{let 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 ) *} } ;($($r :tt ) *) =>{let 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 ) *} } ;}
pub trait Modulus: Copy {
    const MODULUS: u32;
    #[inline]
    fn modulo(x: u32) -> u32 {
        x % Self::MODULUS
    }
}
#[allow(unused_macros)]
macro_rules! make_modulus {
    ($t :ident ,$e :expr ) => {
        #[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
        pub struct $t {}
        impl Modulus for $t {
            const MODULUS: u32 = $e;
        }
    };
}
pub mod modulus {
    use super::*;
    #[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
    pub struct Modulo1000000007 {}
    impl Modulus for Modulo1000000007 {
        const MODULUS: u32 = 1_000_000_007;
    }
    #[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
    pub struct Modulo1000000009 {}
    impl Modulus for Modulo1000000009 {
        const MODULUS: u32 = 1_000_000_009;
    }
    #[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
    pub struct Modulo998244353 {}
    impl Modulus for Modulo998244353 {
        const MODULUS: u32 = 998_244_353;
    }
}
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, Ord, PartialOrd, Hash)]
pub struct MInt<M>
where
    M: Modulus,
{
    x: u32,
    phantom: std::marker::PhantomData<M>,
}
impl<M: Modulus> MInt<M> {
    #[inline]
    pub fn new(x: u32) -> Self {
        Self {
            x: M::modulo(x),
            phantom: std::marker::PhantomData,
        }
    }
    #[inline]
    pub fn new_unchecked(x: u32) -> Self {
        Self {
            x,
            phantom: std::marker::PhantomData,
        }
    }
    #[inline]
    pub fn one() -> Self {
        Self::new_unchecked(1)
    }
    #[inline]
    pub fn zero() -> Self {
        Self::new_unchecked(0)
    }
    #[inline]
    pub fn get_mod() -> u32 {
        M::MODULUS
    }
    #[inline]
    pub fn pow(mut self, mut y: usize) -> Self {
        let mut x = Self::one();
        while y > 0 {
            if y & 1 == 1 {
                x *= self;
            }
            self *= self;
            y >>= 1;
        }
        x
    }
    #[inline]
    pub fn inv(self) -> Self {
        let mut a = self.x;
        let (mut b, mut u, mut s) = (M::MODULUS, 1, 0);
        let k = a.trailing_zeros();
        a >>= k;
        for _ in 0..k {
            if u & 1 == 1 {
                u += M::MODULUS;
            }
            u /= 2;
        }
        while a != b {
            if b < a {
                std::mem::swap(&mut a, &mut b);
                std::mem::swap(&mut u, &mut s);
            }
            b -= a;
            if s < u {
                s += M::MODULUS;
            }
            s -= u;
            let k = b.trailing_zeros();
            b >>= k;
            for _ in 0..k {
                if s & 1 == 1 {
                    s += M::MODULUS;
                }
                s /= 2;
            }
        }
        Self::new_unchecked(s)
    }
}
pub mod modu32_impls {
    use super::*;
    use std::{
        fmt,
        iter::{Product, Sum},
        num::ParseIntError,
        ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign},
        str::FromStr,
    };
    impl<M: Modulus> From<u32> for MInt<M> {
        #[inline]
        fn from(x: u32) -> Self {
            Self::new(x)
        }
    }
    impl<M: Modulus> From<u64> for MInt<M> {
        #[inline]
        fn from(x: u64) -> Self {
            Self::new_unchecked((x % M::MODULUS as u64) as u32)
        }
    }
    impl<M: Modulus> Add for MInt<M> {
        type Output = Self;
        #[inline]
        fn add(self, rhs: Self) -> Self::Output {
            let mut x = self.x + rhs.x;
            if x >= M::MODULUS {
                x -= M::MODULUS;
            }
            Self::new_unchecked(x)
        }
    }
    impl<M: Modulus> Sub for MInt<M> {
        type Output = Self;
        #[inline]
        fn sub(self, rhs: Self) -> Self::Output {
            if self.x < rhs.x {
                Self::new_unchecked(self.x + M::MODULUS - rhs.x)
            } else {
                Self::new_unchecked(self.x - rhs.x)
            }
        }
    }
    impl<M: Modulus> Mul for MInt<M> {
        type Output = Self;
        #[inline]
        fn mul(self, rhs: Self) -> Self::Output {
            Self::new_unchecked((self.x as u64 * rhs.x as u64 % M::MODULUS as u64) as u32)
        }
    }
    impl<M: Modulus> Div for MInt<M> {
        type Output = Self;
        #[inline]
        fn div(self, rhs: Self) -> Self::Output {
            self * rhs.inv()
        }
    }
    impl<M: Modulus> Neg for MInt<M> {
        type Output = Self;
        #[inline]
        fn neg(self) -> Self::Output {
            if self.x == 0 {
                Self::zero()
            } else {
                Self::new_unchecked(M::MODULUS - self.x)
            }
        }
    }
    impl<M: Modulus> Sum for MInt<M> {
        #[inline]
        fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), Add::add)
        }
    }
    impl<M: Modulus> Product for MInt<M> {
        #[inline]
        fn product<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::one(), Mul::mul)
        }
    }
    impl<'a, M: Modulus + 'a> Sum<&'a MInt<M>> for MInt<M> {
        #[inline]
        fn sum<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), Add::add)
        }
    }
    impl<'a, M: Modulus + 'a> Product<&'a MInt<M>> for MInt<M> {
        #[inline]
        fn product<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::one(), Mul::mul)
        }
    }
    impl<M: Modulus> fmt::Display for MInt<M> {
        fn fmt<'a>(&self, f: &mut fmt::Formatter<'a>) -> Result<(), fmt::Error> {
            write!(f, "{}", self.x)
        }
    }
    impl<M: Modulus> FromStr for MInt<M> {
        type Err = ParseIntError;
        #[inline]
        fn from_str(s: &str) -> Result<Self, Self::Err> {
            s.parse::<u32>().map(Self::new)
        }
    }
    macro_rules! modu32_ref_binop {
        ($imp :ident ,$method :ident ,$t :ty ) => {
            impl<M: Modulus> $imp<$t> for &$t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: $t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(*self, other)
                }
            }
            impl<M: Modulus> $imp<&$t> for $t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: &$t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(self, *other)
                }
            }
            impl<M: Modulus> $imp<&$t> for &$t {
                type Output = <$t as $imp<$t>>::Output;
                #[inline]
                fn $method(self, other: &$t) -> <$t as $imp<$t>>::Output {
                    $imp::$method(*self, *other)
                }
            }
        };
    }
    modu32_ref_binop!(Add, add, MInt<M>);
    modu32_ref_binop!(Sub, sub, MInt<M>);
    modu32_ref_binop!(Mul, mul, MInt<M>);
    modu32_ref_binop!(Div, div, MInt<M>);
    macro_rules! modu32_ref_unop {
        ($imp :ident ,$method :ident ,$t :ty ) => {
            impl<M: Modulus> $imp for &$t {
                type Output = <$t as $imp>::Output;
                #[inline]
                fn $method(self) -> <$t as $imp>::Output {
                    $imp::$method(*self)
                }
            }
        };
    }
    modu32_ref_unop!(Neg, neg, MInt<M>);
    macro_rules! modu32_ref_op_assign {
        ($imp :ident ,$method :ident ,$t :ty ,$fromimp :ident ,$frommethod :ident ) => {
            impl<M: Modulus> $imp<$t> for $t {
                #[inline]
                fn $method(&mut self, rhs: $t) {
                    *self = $fromimp::$frommethod(*self, rhs);
                }
            }
            impl<M: Modulus> $imp<&$t> for $t {
                #[inline]
                fn $method(&mut self, other: &$t) {
                    $imp::$method(self, *other);
                }
            }
        };
    }
    modu32_ref_op_assign!(AddAssign, add_assign, MInt<M>, Add, add);
    modu32_ref_op_assign!(SubAssign, sub_assign, MInt<M>, Sub, sub);
    modu32_ref_op_assign!(MulAssign, mul_assign, MInt<M>, Mul, mul);
    modu32_ref_op_assign!(DivAssign, div_assign, MInt<M>, Div, div);
}
fn main() {
    #[allow(unused_imports)]
    use std::io::Write as _;
    let __out = std::io::stdout();
    #[allow(unused_mut, unused_variables)]
    let mut __out = std::io::BufWriter::new(__out.lock());
    #[allow(unused_macros)]
    macro_rules !print {($($arg :tt ) *) =>(::std ::write !(__out ,$($arg ) *) .unwrap () ) }
    #[allow(unused_macros)]
    macro_rules !println {($($arg :tt ) *) =>(::std ::writeln !(__out ,$($arg ) *) .unwrap () ) }
    #[allow(unused_macros)]
    macro_rules! echo {
        ($iter :expr ) => {
            echo!($iter, "\n")
        };
        ($iter :expr ,$sep :expr ) => {
            let mut iter = $iter;
            if let Some(item) = iter.next() {
                print!("{}", item);
            }
            for item in iter {
                print!("{}{}", $sep, item);
            }
            println!();
        };
    }
    input!(a, b, c, d);
    type M = MInt<modulus::Modulo998244353>;
    let e = c - a;
    let f = d - b;
    let mut dp = vec![vec![M::zero(); f + 1]; e + 1];
    dp[0][0] = M::one();
    for i in 0..=e {
        for j in 0..=f {
            if i > 0 {
                let x = dp[i - 1][j] * M::new((b + j) as u32);
                dp[i][j] += x;
            }
            if j > 0 {
                let x = dp[i][j - 1] * M::new((a + i) as u32);
                dp[i][j] += x;
            }
            if i > 0 && j > 0 {
                let x = dp[i - 1][j - 1] * M::new((a + i - 1) as u32) * M::new((b + j - 1) as u32);
                dp[i][j] -= x;
            }
        }
    }
    println!("{}", dp[e][f]);
}