#include<iostream>
using namespace std;
int main()
{
	int k,n,a; 
	int p;
	cin>>n>>k;
	p=n+1-1;
	a=n/2;
	p=p+a;
	p=p-1;
	cout<<p<<endl;
	return 0;
}#include <iostream>
using namespace std;
int main()
{
	long long x,y,z=0,a; 
	cin>>x>>y;
	for(int i=x;i<=y;i++)
	{
		a=0;
		for(int j=2;j<=i;j++)
		{
	
		if(i%j==0);
		{
			a = a+1;
		}
			
		}
		
		if(a!=0)
		{
			z = z+1;
		}	
		
	}
	cout<<z<<endl;
	return 0; 
}