#include <cstdio>
using namespace std;

int main() {
	int n,ans=0,prime[1000000];
	prime[0]=0;
	prime[1]=0;
	for(int i=2;i<1000000;++i){ prime[i]=1; }
	for(int i=2;i<1000000;++i){
		if(prime[i]==1) {
			++ans;
			if(i<1000) for(int j=i*i;j<1000000;j+=i) prime[j]=0;
		}
		prime[i]=ans;
	}
	while(scanf("%d",&n) != EOF) { printf("%d\n",prime[n]); }
	return 0;
}
### Prompt

Please create a solution in Cpp 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>
using namespace std;

int main() {
	int n,ans=0,prime[1000000];
	prime[0]=0;
	prime[1]=0;
	for(int i=2;i<1000000;++i){ prime[i]=1; }
	for(int i=2;i<1000000;++i){
		if(prime[i]==1) {
			++ans;
			if(i<1000) for(int j=i*i;j<1000000;j+=i) prime[j]=0;
		}
		prime[i]=ans;
	}
	while(scanf("%d",&n) != EOF) { printf("%d\n",prime[n]); }
	return 0;
}
```