#include <iostream>
using namespace std;
bool t[999999] = {false};
int main()
{
	int n, c, i, j;
	t[0] = true;
	for (i = 2; i * i <= 999999; i++)
	{
		if (!t[i-1])
		{
			for (j = i+i; j <= 999999; j+=i)
				t[j-1] = true;
		}
	}
	while (cin >> n)
	{
		if (cin.eof()) break;
		for (i = c = 0; i < n; i++)
			if (!t[i]) c++;
		cout << c << endl;
	}
}
### Prompt

Create a solution in Cpp for 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;
bool t[999999] = {false};
int main()
{
	int n, c, i, j;
	t[0] = true;
	for (i = 2; i * i <= 999999; i++)
	{
		if (!t[i-1])
		{
			for (j = i+i; j <= 999999; j+=i)
				t[j-1] = true;
		}
	}
	while (cin >> n)
	{
		if (cin.eof()) break;
		for (i = c = 0; i < n; i++)
			if (!t[i]) c++;
		cout << c << endl;
	}
}
```