#include<cstdio>
using namespace std;
bool prime[1000000];
#define max 1000000
int main(){
	prime[1] = true;
	for(int i = 2; i * i < max; i++){
		if(!prime[i]){
			for(int j = i * i; j < max; j+=i){
				prime[j] = true;
			}
		}
	}
	int n;
	while(scanf("%d",&n) != EOF){
		int ans = 0;
		for(int i = 1; i <= n; i++){
			if(!prime[i])ans++;
		}
		printf("%d\n",ans);
	}
	return 0;
}
### Prompt

In cpp, your task is to solve 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>
using namespace std;
bool prime[1000000];
#define max 1000000
int main(){
	prime[1] = true;
	for(int i = 2; i * i < max; i++){
		if(!prime[i]){
			for(int j = i * i; j < max; j+=i){
				prime[j] = true;
			}
		}
	}
	int n;
	while(scanf("%d",&n) != EOF){
		int ans = 0;
		for(int i = 1; i <= n; i++){
			if(!prime[i])ans++;
		}
		printf("%d\n",ans);
	}
	return 0;
}
```