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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

const (
	initialBufSize = 100000
	maxBufSize     = 10000000
)

var (
	sc = bufio.NewScanner(os.Stdin)
	wt = bufio.NewWriter(os.Stdout)
)

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(next())
	return i
}

func nextInt2() (int, int) {
	return nextInt(), nextInt()
}

func nextInt3() (int, int, int) {
	return nextInt(), nextInt(), nextInt()
}

func nextInt4() (int, int, int, int) {
	return nextInt(), nextInt(), nextInt(), nextInt()
}

func nextInts(n int) []int {
	slice := make([]int, n)
	for i := 0; i < n; i++ {
		slice[i] = nextInt()
	}
	return slice
}

func nextFloat64() float64 {
	f, _ := strconv.ParseFloat(next(), 64)
	return f
}

func nextFloat64s(n int) []float64 {
	slice := make([]float64, n)
	for i := 0; i < n; i++ {
		slice[i] = nextFloat64()
	}
	return slice
}

func putf(format string, a ...interface{}) {
	fmt.Fprintf(wt, format, a...)
}

func puts(a ...interface{}) {
	fmt.Fprintln(wt, a...)
}

func main() {
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, initialBufSize), maxBufSize)
	defer wt.Flush()

	l, r, d := nextInt(), nextInt(), nextInt()
	ans := r/d - (l-1)/d
	puts(ans)
}