Problem:
Score : 600 points

Problem Statement

Snuke is standing on a two-dimensional plane. In one operation, he can move by 1 in the positive x-direction, or move by 1 in the positive y-direction.

Let us define a function f(r, c) as follows:

f(r,c) := (The number of paths from the point (0, 0) to the point (r, c) that Snuke can trace by repeating the operation above)

Given are integers r_1, r_2, c_1, and c_2.
Find the sum of f(i, j) over all pair of integers (i, j) such that r_1 ≤ i ≤ r_2 and c_1 ≤ j ≤ c_2, and compute this value modulo (10^9+7).

Constraints

1 ≤ r_1 ≤ r_2 ≤ 10^6

1 ≤ c_1 ≤ c_2 ≤ 10^6

All values in input are integers.

Input

Input is given from Standard Input in the following format:

r_1 c_1 r_2 c_2

Output

Print the sum of f(i, j) modulo (10^9+7).

Sample Input 1

1 1 2 2

Sample Output 1

14

For example, there are two paths from the point (0, 0) to the point (1, 1): (0,0) → (0,1) → (1,1) and (0,0) → (1,0) → (1,1), so f(1,1)=2.

Similarly, f(1,2)=3, f(2,1)=3, and f(2,2)=6. Thus, the sum is 14.

Sample Input 2

314 159 2653 589

Sample Output 2

602215194

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

#![allow(unused_parens)]
#![allow(unused_imports)]
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
#![allow(unused_mut)]
#![allow(unused_variables)]
#![allow(dead_code)]

use itertools::Itertools;
use proconio::input;
use proconio::marker::{Chars, Usize1};

#[allow(unused_macros)]
#[cfg(debug_assertions)]
macro_rules! mydbg {
    //($arg:expr) => (dbg!($arg))
    //($arg:expr) => (println!("{:?}",$arg));
      ($($a:expr),*) => {
          eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
      }
}
#[cfg(not(debug_assertions))]
macro_rules! mydbg {
    ($($arg:expr),*) => {};
}

macro_rules! echo {
    ($($a:expr),*) => {
          $(println!("{}",$a))*
      }
}

use std::cmp::*;
use std::collections::*;
use std::ops::{Add, Div, Mul, Sub};

#[allow(dead_code)]
static INF_I64: i64 = 92233720368547758;
#[allow(dead_code)]
static INF_I32: i32 = 21474836;
#[allow(dead_code)]
static INF_USIZE: usize = 18446744073709551;
#[allow(dead_code)]
static M_O_D: usize = 1000000007;
#[allow(dead_code)]
static PAI: f64 = 3.1415926535897932;

trait IteratorExt: Iterator {
    fn toVec(self) -> Vec<Self::Item>;
}

impl<T: Iterator> IteratorExt for T {
    fn toVec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

trait CharExt {
    fn toNum(&self) -> usize;
    fn toAlphabetIndex(&self) -> usize;
    fn toNumIndex(&self) -> usize;
}
impl CharExt for char {
    fn toNum(&self) -> usize {
        return *self as usize;
    }
    fn toAlphabetIndex(&self) -> usize {
        return self.toNum() - 'a' as usize;
    }
    fn toNumIndex(&self) -> usize {
        return self.toNum() - '0' as usize;
    }
}

trait VectorExt {
    fn joinToString(&self, s: &str) -> String;
}
impl<T: ToString> VectorExt for Vec<T> {
    fn joinToString(&self, s: &str) -> String {
        return self
            .iter()
            .map(|x| x.to_string())
            .collect::<Vec<_>>()
            .join(s);
    }
}

trait StringExt {
    fn get_reverse(&self) -> String;
}
impl StringExt for String {
    fn get_reverse(&self) -> String {
        self.chars().rev().collect::<String>()
    }
}

trait UsizeExt {
    fn pow(&self, n: usize) -> usize;
}
impl UsizeExt for usize {
    fn pow(&self, n: usize) -> usize {
        return ((*self as u64).pow(n as u32)) as usize;
    }
}

#[derive(Debug, Copy, Clone)]
pub struct ModInt {
    x: i64,
    global_mod: i64,
}
impl ModInt {
    pub fn new(p: i64) -> Self {
        let gm = 1000000007;
        let a = (p % gm + gm) % gm;
        return ModInt {
            x: a,
            global_mod: gm,
        };
    }
    pub fn inv(self) -> Self {
        return self.pow(self.global_mod - 2);
    }
    pub fn pow(self, t: i64) -> Self {
        if (t == 0) {
            return ModInt::new(1);
        };
        let mut a = self.pow(t >> 1);
        a = a * a;
        if (t & 1 != 0) {
            a = a * self
        };
        return a;
    }
}
impl Add for ModInt {
    type Output = ModInt;
    fn add(self, other: ModInt) -> ModInt {
        let ret = self.x + other.x;
        return ModInt::new(ret);
    }
}
impl Sub for ModInt {
    type Output = ModInt;
    fn sub(self, other: ModInt) -> ModInt {
        let ret = self.x - other.x;
        return ModInt::new(ret);
    }
}
impl Mul for ModInt {
    type Output = ModInt;
    fn mul(self, other: ModInt) -> ModInt {
        let ret = self.x * other.x;
        return ModInt::new(ret);
    }
}
impl Div for ModInt {
    type Output = ModInt;
    fn div(self, other: ModInt) -> ModInt {
        let ret = self.x * other.inv().x;
        return ModInt::new(ret);
    }
}
impl std::string::ToString for ModInt {
    fn to_string(&self) -> String {
        return self.x.to_string();
    }
}
pub struct Combination {
    fact: Vec<ModInt>,
    ifact: Vec<ModInt>,
}
impl Combination {
    pub fn new(n: i32) -> Self {
        if n > 3000000 {
            panic!("error");
        }
        let mut fact = vec![ModInt::new(0); (n + 1) as usize];
        let mut ifact = vec![ModInt::new(0); (n + 1) as usize];
        fact[0] = ModInt::new(1);
        for i in 1..n + 1 {
            fact[i as usize] = fact[(i - 1) as usize] * ModInt::new(i as i64)
        }
        ifact[n as usize] = fact[n as usize].inv();
        for i in (1..n + 1).rev() {
            ifact[(i - 1) as usize] = ifact[i as usize] * ModInt::new(i as i64)
        }
        let a = Combination {
            fact: fact,
            ifact: ifact,
        };
        return a;
    }
    #[macro_use]
    pub fn gen(&mut self, n: i32, k: i32) -> ModInt {
        if (k < 0 || k > n) {
            return ModInt::new(0 as i64);
        };
        return self.fact[n as usize] * self.ifact[k as usize] * self.ifact[(n - k) as usize];
    }
    pub fn P(&mut self, n: i32, k: i32) -> ModInt {
        self.fact[n as usize] * self.ifact[(n - k) as usize]
    }
}

fn main() {
    input! {
       mut r1:i32,
       mut c1:i32,
       mut r2:i32,
       mut c2:i32,
    }
    let mut cmb = Combination::new(2000020 as i32);
    let mut a = cmb.gen(r2 + c2 + 2, r2 + 1) - ModInt::new(1);
    let mut b = cmb.gen(r2 + c1 + 2 - 1, r2 + 1) - ModInt::new(1);
    let mut c = cmb.gen(r1 + c2 + 2 - 1, c2 + 1) - ModInt::new(1);
    let mut d = cmb.gen(r1 + c1 + 2 - 2, r1) - ModInt::new(1);

    let ans = a + d - c - b;
    echo!(ans.to_string());
}