#include <stdio.h>
#include <time.h>
int v[1000001],n,i,j;
main(){

long long suma=0;

FILE  *f=fopen("fractii.in","r");
fscanf(f,"%d",&n);
fclose(f);
for (i=1;i<=n;++i)
    v[i]=i-1;
for (i=2;i<=n;++i){
    suma+=v[i];
    for (j=2*i;j<=n;j+=i)
        v[j]-=v[i];
}
suma=suma*2+1;
f=fopen("fractii.out","w");
fprintf(f,"%lld",suma);
}