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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve(new ConsoleInput(Console.In, ' '));
        }

        public void Solve(ConsoleInput cin)
        {

            int L = cin.ReadInt;
            int R = cin.ReadInt;
            int d = cin.ReadInt;
            int counter = 0;
            int i = L;

            for (i = L; i < R + 1; i++) {
                if ((i % d) == 0)
                {
                    counter++;
                }
            }

            WriteLine(counter);
            //var nk = Console.ReadLine().Split(' ');
            //var n = int.Parse(nk[0]);
            //var k = int.Parse(nk[1]);

            //var t = new int[n][];
            //for (int i =0; i < n;i++) {
            //    t[i] = cin.ReadIntArray(n);
            //}

            //int n = cin.ReadInt;
            //int K = cin.ReadInt;

            //int[] array = new int[n];

            //for (int i =0; i < n; i++) {
            //    array[i] = cin.ReadInt;
            //}

            //for (int i =0; i < n; i++) {
            //    if (array[i] == 0) {
            //        WriteLine(n);
            //    }
            //}

            //int res = 0;
            //int right = 0;
            //long mult = 1;

            //for (int left = 0; left < n; left++) {
            //    while (right < n && mult * array[right] <= K) {
            //        mult *= array[right];
            //        right++;
            //    }

            //    res = Math.Max(res, right - left);
            //    if (left == right) right++;
            //    else mult /= array[left];


            //}
            //WriteLine(res);
        }
    }

    public class ConsoleInput
    {
        private readonly System.IO.TextReader _stream;
        private char _separator = ' ';
        private Queue<string> inputStream;
        public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
        {
            this._separator = separator;
            this._stream = stream;
            inputStream = new Queue<string>();
        }
        public string Read
        {
            get
            {
                if (inputStream.Count != 0) return inputStream.Dequeue();
                string[] tmp = _stream.ReadLine().Split(_separator);
                for (int i = 0; i < tmp.Length; ++i)
                    inputStream.Enqueue(tmp[i]);
                return inputStream.Dequeue();
            }
        }
        public string ReadLine { get { return _stream.ReadLine(); } }
        public int ReadInt { get { return int.Parse(Read); } }
        public long ReadLong { get { return long.Parse(Read); } }
        public double ReadDouble { get { return double.Parse(Read); } }
        public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
        public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
        public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
    }
}