#include<stdio.h>
#include<stdlib.h>
int n,phi[2000001],i,j,s;
int main()
  {
   freopen("fractii.in","rt",stdin);
   freopen("fractii.out","wt",stdout);
   scanf("%d",&n);
   for(i=2;i<=n;++i) phi[i]=n-1;
   for(i=2;i<=n;++i)
       {for(j=2;j*i<=n;++j) phi[i]--,phi[i*j]--;
        s+=phi[i];
       }
   printf("%d",s+n);
   //system("PAUSE");
   return 0;
  }