#include<stdio.h>
using namespace std;
int main()
{
    int p,q,n,nr,i,j,x,y;
    char prim[1000000];
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    nr=2*n-1;
    for(i=2;i<=n;i++)
    prim[i]=1;
    for(i=2;i<=n;i++)
    if(prim[i]==1)
    {
        for(j=i*i;j<=n;j=j+i)
        prim[j]=0;
    }
    for(p=2;p<=n;p++)
    {
        for(q=2;q<=n;q++)
        {
            if(p!=q && ((prim[p]==1 && prim[q]==0) || (prim[p]==0 && prim[q]==1) || (prim[p]==1 && prim[q]==1)))
            {
                x=p;y=q;
                while(x!=y)
                if(x>y)
                x=x-y;
                else
                y=y-x;
                if(x==1)
                nr++;
            }
        }
    }
    printf("%d",nr);
    return 0;
}