#include <stdio.h>

int main() {
    long v[1000001],n,s=0,i,j;
    FILE *f;
    f=fopen("fractii.in","r"); fscanf(f,"%ld",&n); fclose(f);
    for (i=2; i<=n; i++) {
        v[i]=i-1;
        if (i<=(int)n/2) {
            j=2;
            while (i*j<=n) { v[i*j]=v[i*j]-v[i]; j++; }
            }
        s+=v[i];
    }
    s=s*2+1;
    f=fopen("fractii.out","w"); fprintf(f,"%ld",s); fclose(f);
    return 0;
}