#include <stdio.h>
#include <stdlib.h>

long long euler[1000001];
int main()
{
    int n, i, j;
    FILE*fi,*fo;
    fi=fopen("fractii.in","r");
    fo=fopen("fractii.out","w");
    fscanf(fi,"%d", &n);
    for(i=1;i<=n;i++)
        euler[i]=i;
    for(i=2;i<=n;i++)
        if(euler[i]==i)
            for(j=i;j<=n;j+=i)
                euler[j]=euler[j]*(i-1)/i;

    long long sum=0LL;
    for(i=1;i<=n;i++)
        sum+=1LL*euler[i];
    fprintf(fo,"%lld", 2LL*sum-1LL);
    fclose(fi);
    fclose(fo);
    return 0;
}