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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
using namespace std;

#include <math.h>
#include <iomanip>
#include <vector>
#include <queue>
#include <climits>
using Graph = vector<vector<int>>;
const double PI = 3.14159265358979323846;



long long modpow(long long a, long long n, long long mod) {
	long long res = 1;
	while (n > 0) {
		if (n & 1) res = res * a % mod;
		a = a * a % mod;
		n >>= 1;
	}
	return res;
}


//約数をベクトル形式で返す
vector<int> vect_yakusuu(int n) {
	vector<int> ret;
	for (int i = 1; i*i <= n; i++) {
		if (n%i == 0) {
			ret.push_back(i);
			if (i*i != n) ret.push_back(n / i);
		}
	}
	sort(begin(ret), end(ret));
	return ret;
}



int main() {

	long long ans;
	int L, R, D;

	cin >> L >> R >> D;

	ans = R/D - (L - 1) / D;


	cout << ans << endl;

	cin >> ans;

	return 0;


}