#include<stdio.h>
const int size=1000000;
int main(){
  int i,k,n;
  int data[size];
  int sum[size];
  for(i=2;i<size;i++){
    data[i]=1;
  }
  for(i=2;i<size;i++){
    if(data[i]){
      for(k=2*i;k<=size;k+=i){
        data[k]=0;
      }
    }
  }
  for(i=2;i<size;i++){
    sum[i+1]=sum[i]+data[i];
  }
  while(scanf("%d",&n)!=EOF){
    printf("%d\n",sum[n+1]);
  }
}
### 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<stdio.h>
const int size=1000000;
int main(){
  int i,k,n;
  int data[size];
  int sum[size];
  for(i=2;i<size;i++){
    data[i]=1;
  }
  for(i=2;i<size;i++){
    if(data[i]){
      for(k=2*i;k<=size;k+=i){
        data[k]=0;
      }
    }
  }
  for(i=2;i<size;i++){
    sum[i+1]=sum[i]+data[i];
  }
  while(scanf("%d",&n)!=EOF){
    printf("%d\n",sum[n+1]);
  }
}
```