#include <cstdio>

const int size = 1000005;
int n;
bool ispm[size];

int get(int n) {
	int ans = 0;
	for ( int i = 1; i <= n; i ++ ) ispm[i] = 1;
	for ( int i = 2; i <= n; i ++ ) {
		if(ispm[i]) {
			ans ++;
			for ( int j = 2*i; j <= n; j += i) ispm[j] = 0;
		}
	}

	return ans;
}

int main() {
	while( scanf("%d", &n) != EOF ) {
		printf("%d\n", get(n));
	}

	return 0;
}
### Prompt

Your task is to create 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>

const int size = 1000005;
int n;
bool ispm[size];

int get(int n) {
	int ans = 0;
	for ( int i = 1; i <= n; i ++ ) ispm[i] = 1;
	for ( int i = 2; i <= n; i ++ ) {
		if(ispm[i]) {
			ans ++;
			for ( int j = 2*i; j <= n; j += i) ispm[j] = 0;
		}
	}

	return ans;
}

int main() {
	while( scanf("%d", &n) != EOF ) {
		printf("%d\n", get(n));
	}

	return 0;
}
```