#include<cstdio>
#include<string.h>

using namespace std;

int main(){
	static bool p[1000000];
	memset(p,true,sizeof(p));
	p[0] = false;
	p[1] = false;
	for(int i= 2;i<1000000;i++){
		if(p[i]){
			for(int j=i*2;j<1000000;j+=i){
				p[j] = false;
			}
		}
	}
	int n,ans;
	while(!(scanf("%d",&n)==EOF)){
		ans=0;
		for(int j=2;j<=n;j++){
			if(p[j])ans++;
		}
		printf("%d\n",ans);
	}
}
### Prompt

Your challenge is to write a Cpp solution to the following problem:

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<cstdio>
#include<string.h>

using namespace std;

int main(){
	static bool p[1000000];
	memset(p,true,sizeof(p));
	p[0] = false;
	p[1] = false;
	for(int i= 2;i<1000000;i++){
		if(p[i]){
			for(int j=i*2;j<1000000;j+=i){
				p[j] = false;
			}
		}
	}
	int n,ans;
	while(!(scanf("%d",&n)==EOF)){
		ans=0;
		for(int j=2;j<=n;j++){
			if(p[j])ans++;
		}
		printf("%d\n",ans);
	}
}
```