#include<iostream>
using namespace std;

int main(){
int n,a;
int pri[99999];
pri[0]=2;
int ans=1;
while(cin>>n){
ans=1;
for(int i=3;i<n+1;i++){
pri[ans]=i;
for(int j=0;j<ans&&pri[j]*pri[j]<i+1;j++){
a=i%pri[j];
if(a==0){
ans--;
break;}
}
ans++;
}
if(n==1){ans=0;}
cout<<ans<<endl;}}
### Prompt

Please formulate 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<iostream>
using namespace std;

int main(){
int n,a;
int pri[99999];
pri[0]=2;
int ans=1;
while(cin>>n){
ans=1;
for(int i=3;i<n+1;i++){
pri[ans]=i;
for(int j=0;j<ans&&pri[j]*pri[j]<i+1;j++){
a=i%pri[j];
if(a==0){
ans--;
break;}
}
ans++;
}
if(n==1){ans=0;}
cout<<ans<<endl;}}
```