#include <stdio.h>
 #include <string.h>
int main(void) {
    int n,i,c,k,prime[999999] = {0},t;
    for(i = 2; 999999 >= i; i++){
        if(!prime[i])
    		for(c = i*2; 999999 >= c; c += i)prime[c] = 1;
    }
    while(scanf("%d",&n) != EOF){
    	i = 0;
    for(c = 2; n >= c; c++){
        	if(!prime[c]) i++;
        }
    printf("%d\n",i);
    }
     
    return 0;
}
### Prompt

Your challenge is to write a CPP solution 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 <stdio.h>
 #include <string.h>
int main(void) {
    int n,i,c,k,prime[999999] = {0},t;
    for(i = 2; 999999 >= i; i++){
        if(!prime[i])
    		for(c = i*2; 999999 >= c; c += i)prime[c] = 1;
    }
    while(scanf("%d",&n) != EOF){
    	i = 0;
    for(c = 2; n >= c; c++){
        	if(!prime[c]) i++;
        }
    printf("%d\n",i);
    }
     
    return 0;
}
```