#include<stdio.h>
#include<math.h>
int main(){
	int a[999999]={0},i,j;
	a[1]=1;
	for(i=2;i<=999999;i++){
		if(a[i]==0)for(int j=i*2;j<=999999;j+=i)a[j]=1;}
	int n;
	while(~scanf("%d",&n)){
		int sum=0;
		for(i=1;i<=n;i++){
			if(a[i]==0)sum++;}
		printf("%d\n",sum);}
	return 0;}

### Prompt

Please provide a cpp coded solution to the problem described below:

Write a program which reads an integer n and prints the number of prime numbers which are less than or equal to n. A prime number is a natural number which has exactly two distinct natural number divisors: 1 and itself. For example, the first four prime numbers are: 2, 3, 5 and 7.



Input

Input consists of several datasets. Each dataset has an integer n (1 ≤ n ≤ 999,999) in a line.

The number of datasets is less than or equal to 30.

Output

For each dataset, prints the number of prime numbers.

Example

Input

10
3
11


Output

4
2
5

### Response

```cpp
#include<stdio.h>
#include<math.h>
int main(){
	int a[999999]={0},i,j;
	a[1]=1;
	for(i=2;i<=999999;i++){
		if(a[i]==0)for(int j=i*2;j<=999999;j+=i)a[j]=1;}
	int n;
	while(~scanf("%d",&n)){
		int sum=0;
		for(i=1;i<=n;i++){
			if(a[i]==0)sum++;}
		printf("%d\n",sum);}
	return 0;}

```