#include <stdio.h>

int phi[1000001];
int main()  {
FILE *fin = fopen("fractii.in", "r");
FILE *fout = fopen("fractii.out", "w");
int N;
fscanf(fin, "%d", &N);
for (int i = 1; i <= N; ++i)
    phi[i] = i-1;
for (int i = 2; i * i <= N; ++i)
    for (int j = 2*i; j <= N; j += i)
        phi[j] -= phi[i];
int total = 0;
for(int i = 1;i <= N;i++)  {
    total += phi[i];
}
fprintf(fout, "%d", total*2+1);
fclose(fin);
fclose(fout);
return 0;
}