#include<stdio.h>

int prime[1000000];
bool flag[1000000];

void solve(int n)
{
	int ans=0;
	for(int i=2;i<=n;i++)
	{
		if(flag[i])
		{
			prime[ans++]=i;
			for(int j=2*i;j<=n;j+=i)
				flag[j]=false;
		}
	}
	printf("%d\n",ans);
}

int main()
{
	int data;
	while(scanf("%d",&data)!=EOF)
	{
		for(int i=0;i<=data;i++)
			flag[i]=true;
		flag[0]=flag[1]=false;
		solve(data);
	}
}
### 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<stdio.h>

int prime[1000000];
bool flag[1000000];

void solve(int n)
{
	int ans=0;
	for(int i=2;i<=n;i++)
	{
		if(flag[i])
		{
			prime[ans++]=i;
			for(int j=2*i;j<=n;j+=i)
				flag[j]=false;
		}
	}
	printf("%d\n",ans);
}

int main()
{
	int data;
	while(scanf("%d",&data)!=EOF)
	{
		for(int i=0;i<=data;i++)
			flag[i]=true;
		flag[0]=flag[1]=false;
		solve(data);
	}
}
```