#include<iostream>
#include<cstring>

int PrimeCount(int n){
	int A[n+5];
	memset(A,0,sizeof(A));//0は素数
	for(int i=2;i*i<=n;i++){
		if(A[i]==0){
			for(int j=i*2;j<=n;j+=i){
				A[j]=1;
			}
		}
	}
	int count=0;
	for(int i=2;i<=n;i++){
		if(A[i]==0) count++;
	}
	return count;
}

int main(void){
	int n;
	while(std::cin>>n){
		std::cout<<PrimeCount(n)<<std::endl;
	}
	return 0;
}


### Prompt

Please provide a CPP coded solution to the problem described below:

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<iostream>
#include<cstring>

int PrimeCount(int n){
	int A[n+5];
	memset(A,0,sizeof(A));//0は素数
	for(int i=2;i*i<=n;i++){
		if(A[i]==0){
			for(int j=i*2;j<=n;j+=i){
				A[j]=1;
			}
		}
	}
	int count=0;
	for(int i=2;i<=n;i++){
		if(A[i]==0) count++;
	}
	return count;
}

int main(void){
	int n;
	while(std::cin>>n){
		std::cout<<PrimeCount(n)<<std::endl;
	}
	return 0;
}


```