#include <bits/stdc++.h>

using namespace std;

int n,np[1000000];
bool isp[1000000];

int main()
{
    memset(isp,1,sizeof isp);
    isp[0]=isp[1]=0;
    for(int i=2;i<1000;i++)
        if (isp[i]) for(int j=i*i;j<1000000;j+=i) isp[j]=false;
    for(int i=1;i<1000000;i++) np[i]+=np[i-1]+isp[i];
    while (~scanf("%d",&n)) printf("%d\n",np[n]);
    return 0;
}


### Prompt

Construct a CPP code solution to the problem outlined:

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 <bits/stdc++.h>

using namespace std;

int n,np[1000000];
bool isp[1000000];

int main()
{
    memset(isp,1,sizeof isp);
    isp[0]=isp[1]=0;
    for(int i=2;i<1000;i++)
        if (isp[i]) for(int j=i*i;j<1000000;j+=i) isp[j]=false;
    for(int i=1;i<1000000;i++) np[i]+=np[i-1]+isp[i];
    while (~scanf("%d",&n)) printf("%d\n",np[n]);
    return 0;
}


```