#include<stdio.h>
int j,N,phi[1000000];
long long ss;
int main() {
FILE *f,*g;
f=fopen("fractii.in","r");
g=fopen("fractii.out","w");
fscanf(f,"%d",&N);
for (int i=1;i<=N;i++) phi[i]=i;

for (int i=2;i<=N;i++) {
   if (phi[i]==i)
      for (j=i;j<=N;j+=i) phi[j] /=i, phi[j] *= (i-1);
ss=ss+phi[i];
}
fprintf(g,"%lld",ss*2+1);
fclose(g);
return 0;
}