#include <cstdio>

long MAX=999999;

int main(void){
    long int s[1000000]={0},k=0,i,j,n;
    
    for(i=2;i<=MAX;i++){
        if( !s[i] ){
            k++;
            for(j=2;j*i<=MAX;j++){
                s[j*i]=-1;
            }
        }
        s[i]=k;
    }
    
    
    while(EOF != scanf("%ld",&n)){
        printf("%ld\n",s[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 <cstdio>

long MAX=999999;

int main(void){
    long int s[1000000]={0},k=0,i,j,n;
    
    for(i=2;i<=MAX;i++){
        if( !s[i] ){
            k++;
            for(j=2;j*i<=MAX;j++){
                s[j*i]=-1;
            }
        }
        s[i]=k;
    }
    
    
    while(EOF != scanf("%ld",&n)){
        printf("%ld\n",s[n]);
    }
    
    
    return 0;
}
```