#include<stdio.h>
int flg[1000000];
int main(void)
{
    int n,i,j,x;
	
    while(scanf("%d",&n)!=EOF){
		for(i=2;i<=n;i++)	{
			flg[i]=1;
		}
		for(i=2;i*i<=n;i++){
			if(flg[i]==1){
				for(j=2;j*i<=n;j++){
					flg[i*j]=0;
				}
			}
		}
		x=0;
		for(i=2;i<=n;i++)	{
			if(flg[i]==1){
				x++;
			}
		}
		printf("%d\n",x);
	}
	return 0;
}
### Prompt

Please formulate 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 flg[1000000];
int main(void)
{
    int n,i,j,x;
	
    while(scanf("%d",&n)!=EOF){
		for(i=2;i<=n;i++)	{
			flg[i]=1;
		}
		for(i=2;i*i<=n;i++){
			if(flg[i]==1){
				for(j=2;j*i<=n;j++){
					flg[i*j]=0;
				}
			}
		}
		x=0;
		for(i=2;i<=n;i++)	{
			if(flg[i]==1){
				x++;
			}
		}
		printf("%d\n",x);
	}
	return 0;
}
```