#include<cstdio>
int n,ans;
bool p[1000005]={1,1};
int main()
{
	int i,j;
	for(i=2;i<=997;i++)
		if(!p[i])
			for(j=i;j*i<1000000;j++)
				p[j*i]=1;
	while(~scanf("%d",&n))
	{
		ans=0;
		for(i=2;i<=n;i++)
			if(!p[i]) ans++;
		printf("%d\n",ans);
	}
}
### Prompt

Generate 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>
int n,ans;
bool p[1000005]={1,1};
int main()
{
	int i,j;
	for(i=2;i<=997;i++)
		if(!p[i])
			for(j=i;j*i<1000000;j++)
				p[j*i]=1;
	while(~scanf("%d",&n))
	{
		ans=0;
		for(i=2;i<=n;i++)
			if(!p[i]) ans++;
		printf("%d\n",ans);
	}
}
```