Problem:
Score : 100 points

Problem Statement

How many multiples of d are there among the integers between L and R (inclusive)?

Constraints

All values in input are integers.

1 \leq L \leq R \leq 100

1 \leq d \leq 100

Input

Input is given from Standard Input in the following format:

L R d

Output

Print the number of multiples of d among the integers between L and R (inclusive).

Sample Input 1

5 10 2

Sample Output 1

3

Among the integers between 5 and 10, there are three multiples of 2: 6, 8, and 10.

Sample Input 2

6 20 7

Sample Output 2

2

Among the integers between 6 and 20, there are two multiples of 7: 7 and 14.

Sample Input 3

1 100 1

Sample Output 3

100

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

use std::io::*;
use std::str::FromStr;
use std::cmp;
use std::collections::HashMap;
use std::collections::HashSet;
use std::char;
use std::cmp::{min, max};
use itertools::Itertools;
use std::ops::{Add, AddAssign};
use num_integer::{Integer, gcd, lcm};
use std::collections::VecDeque;
use smallvec::alloc::collections::LinkedList;
use regex::internal::Char;
use std::iter::once;

fn read<T: FromStr>(stdin: &mut StdinLock) -> T {
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn read_tuple2<T: FromStr, S: FromStr>(stdin: &mut StdinLock) -> (T, S) {
    let a = read(stdin);
    let b = read(stdin);
    (a, b)
}

fn read_tuple3<T: FromStr, S: FromStr, R: FromStr>(stdin: &mut StdinLock) -> (T, S, R) {
    let a = read(stdin);
    let b = read(stdin);
    let c = read(stdin);
    (a, b, c)
}

fn lower_bound<T: Copy, F>(v: &Vec<T>, f: F) -> Option<usize> where
    F: Fn(T) -> bool
{
    let mut left = 0;
    let mut right = v.len() - 1;
    if !f(v[left]) {
        return None;
    }
    if f(v[right]) {
        return Some(right);
    }
    loop {
        if right - left == 1 {
            return Some(left);
        }
        let mid = (left + right) / 2;
        if f(v[mid]) {
            left = mid;
        } else {
            right = mid;
        }
    }
}


fn main() {
    // template
    let stdin = stdin();
    let mut stdin = stdin.lock();
    let out = stdout();
    let mut out = BufWriter::new(out.lock());
    // template ends
    let (l, r, d): (u32, u32, u32) = read_tuple3(&mut stdin);
    let mut ans = 0;
    for i in (l..r+1) {
        if i % d == 0 {
            ans += 1;
        }
    }
    write!(out, "{}", ans);

}