#include<stdio.h>


int main()
{
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);
	int n, c[100];
	scanf("%d",&n) ;
	int i, j;
	for ( i = 1; i <= n; i++)
			c[i] = 1;	
	for ( i = 2; i <= n; i++)
	{
		if(c[i] == 1)
			for( j = 2; j * i <= n; j++)
				c[i*j] = 0;
	}
	int x = 1;
	for ( i = 1; i <= n; i++){
		if(c[i] == 1) 
			{
				for ( j = 1;j <= n; j++){
					if (i != j)
						x++;				
				}
			}
		}
		printf("%d", x);
	return 0;
}