#include<bits/stdc++.h>
using namespace std;
int prime[1000000];
int main(){
    fill_n(prime,1000000,1);
    prime[0]=prime[1]=0;

    for(int i=2;i<1000000;i++){
        prime[i]+=prime[i-1];
        if(prime[i]==prime[i-1])continue;
        for(int j=i+i;j<1000000;j+=i)prime[j]=0;
    }

    int n;
    while(scanf("%d",&n)!=EOF)printf("%d\n",prime[n]);

    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<bits/stdc++.h>
using namespace std;
int prime[1000000];
int main(){
    fill_n(prime,1000000,1);
    prime[0]=prime[1]=0;

    for(int i=2;i<1000000;i++){
        prime[i]+=prime[i-1];
        if(prime[i]==prime[i-1])continue;
        for(int j=i+i;j<1000000;j+=i)prime[j]=0;
    }

    int n;
    while(scanf("%d",&n)!=EOF)printf("%d\n",prime[n]);

    return 0;
}
```