#include <cstdio>
bool d[1000000];
int c[999999];
int main() {
    int i,j,r=0,n;
	for(i=4;i<=999999;i+=2)d[i]=true;
    for(i=2;i*i<=999999;i++) {
        if(d[i])continue;
        for(j=i*2;j<=999999;j+=i)d[j]=true;
    }
	for(i=1;i<999999;i++) {
		c[i]=c[i-1];
		if(!d[i+1])c[i]++;
	}
    while(scanf("%d",&n)!=EOF) {
        printf("%d\n",c[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 <cstdio>
bool d[1000000];
int c[999999];
int main() {
    int i,j,r=0,n;
	for(i=4;i<=999999;i+=2)d[i]=true;
    for(i=2;i*i<=999999;i++) {
        if(d[i])continue;
        for(j=i*2;j<=999999;j+=i)d[j]=true;
    }
	for(i=1;i<999999;i++) {
		c[i]=c[i-1];
		if(!d[i+1])c[i]++;
	}
    while(scanf("%d",&n)!=EOF) {
        printf("%d\n",c[n-1]);
    }
}
```