#include <iostream>
#define N 1000001
using namespace std;
long long a[N],n,i,j;
int main()
{
    for(i=1;i<N;i++)a[i]=i%2?i:i/2;
    for(i=3;i<N;i+=2)
    if(a[i]==i)
    for(j=i;j<N;j+=i)
    a[j]=a[j]-a[j]/i;
    for(i=3;i<N;i++) a[i]+=a[i-1];
    while(cin>>n&&n) cout<<a[n]<<endl;
    return 0;
}