#include <iostream>
using namespace std;
int main(){
  int NUM = 1000000;
  bool prime[NUM];
  prime[0] = false;prime[1] = false;
  for(int i=2;i<NUM;i++)prime[i] = true;
  for(int i=2;i*i<NUM;i++)
    for(int k=2;i*k<NUM;k++)
      prime[i*k]=false;

	int primeNum[NUM];
	for(int i=0,c=0;i<NUM;i++){
		prime[i]&&c++;
		primeNum[i] = c;
	}
	for(int n;cin>>n;cout<<primeNum[n]<<endl);
}
### 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 <iostream>
using namespace std;
int main(){
  int NUM = 1000000;
  bool prime[NUM];
  prime[0] = false;prime[1] = false;
  for(int i=2;i<NUM;i++)prime[i] = true;
  for(int i=2;i*i<NUM;i++)
    for(int k=2;i*k<NUM;k++)
      prime[i*k]=false;

	int primeNum[NUM];
	for(int i=0,c=0;i<NUM;i++){
		prime[i]&&c++;
		primeNum[i] = c;
	}
	for(int n;cin>>n;cout<<primeNum[n]<<endl);
}
```