# include <stdio.h>
# include <stdlib.h>

# define MAX_N 1000001

char ciur[MAX_N];
int phi[MAX_N];

int main() {
    FILE *fin = fopen( "fractii.in", "r" ), *fout = fopen( "fractii.out", "w" );

    int n, i, j;
    unsigned long long S;

    fscanf( fin, "%d", &n );

    phi[1] = 1;
    for ( i = 2; i <= n; i ++ )
        phi[i] = i - 1;

    for ( i = 2; i <= n; i ++ )
        for ( j = 2 * i; j <= n; j += i )
            phi[j] -= phi[i];

    S = 0;
    for ( i = 1; i <= n; i ++ )
        S += phi[i];

    fprintf( fout, "%llu", S * 2 - 1 );

    fclose( fin );
    fclose( fout );

    return 0;
}