#include<stdio.h>
int i,cat,n,cate,cat2,ci,d;
int prim(int x){
    int j;
    for(j=2;j<=n;j++){
        if(x%j==0)
            return 1;
    }
    return 0;
}

int main(){
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    cate=1;
    for(i=2;i<=n;i++){
        if(prim(i)==1){
        ci=i;
        cat=i;
        cat2=1;
        d=2;
        while(ci!=1){
            if(ci%d==0){
                cat=cat*(d-1);
                cat2=cat2*d;
                while(ci%d==0){
                    ci/=d;
                }
            }
            d++;
        }
        cate+=(cat/cat2);
    }
    }
    cate=(cate-1)*2+1;
    printf("%d",cate);
    return 0;
}