#include <stdio.h>

int ans[1000000];

int main()
{
	int n;
	int i,j;
	int an;
	while(scanf("%d",&n) != EOF){
		for(i = 0; i <= n; i++){
			ans[i] = 1;
		}
		for(i = 2; i <= 1000 && i <= n; i++){
			if(ans[i]){
				for(j = 2; i * j <= n; j++){
					ans[i * j] = 0;
				}
			}
		}
		an = 0;
		for(i = 2; i <= n; i++){
			if(ans[i]){
				an++;
			}
		}
		printf("%d\n",an);
	}
	return 0;
}
### 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 <stdio.h>

int ans[1000000];

int main()
{
	int n;
	int i,j;
	int an;
	while(scanf("%d",&n) != EOF){
		for(i = 0; i <= n; i++){
			ans[i] = 1;
		}
		for(i = 2; i <= 1000 && i <= n; i++){
			if(ans[i]){
				for(j = 2; i * j <= n; j++){
					ans[i * j] = 0;
				}
			}
		}
		an = 0;
		for(i = 2; i <= n; i++){
			if(ans[i]){
				an++;
			}
		}
		printf("%d\n",an);
	}
	return 0;
}
```