#include"stdio.h"

int p[1000000];
int i,j,f;
int n;
int ans;

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

Create a solution in CPP for 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"stdio.h"

int p[1000000];
int i,j,f;
int n;
int ans;

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