#include<stdio.h>
#include<math.h>
int nr[1000000],prim[100000];
int main(){
	FILE*in=fopen("fractii.in","r");
	FILE*out=fopen("fractii.out","w");
	int n,i,a,j,s=0,pr;
	fscanf(in,"%d",&n);
	if(n==1){
		fprintf(out,"1\n");
		return 0;
	}
	if(n==2){
		fprintf(out,"3\n");
		return 0;
	}
	
	i=4;
	while(i<=n){
		nr[i]=1;
		i=i+2;
	}
	for(i=3;i<=n;i=i+2){
		pr=1;
		if(nr[i]==0){
			for(j=3;((j*j<=i)&&(pr));j=j+2){
				if(i%j==0)
					pr=0;
			}
			if(pr){
				j=i+i;
				while(j<=n){
					nr[j]=1;
					j=j+i;
				}
			}
		}
	}
	prim[0]=2;
	j=1;
	for(i=3;i<=n/2;i=i+2){
		if(nr[i]==0){
			prim[j]=i;
			j++;
		}
	}
	i=0;
	
	s=n;
	if(n%2==0)
		s=s+n/2;
	if(n%2==1)
		s=s+n/2+1;
	float p;
	for(i=3;i<=n;i++){
		a=i;
		j=0;
		p=1;
		while(prim[j]<=i){
			if(i%prim[j]==0)
				p=p*(((float)prim[j]-1)/prim[j]);
			j++;
		}
		s=s+(ceil(n*p));
		
	}
	
	fprintf(out,"%d\n",s);
	
	
	return 0;
}