#include <fstream>

long long* phi;

std::fstream fi ("fractii.in", std::ios::in);
std::fstream fo ("fractii.out", std::ios::out);

int main (void) {
    unsigned long long n, res = 0;
    
    fi >> n;
    phi = (long long*) malloc ((n + 10) * sizeof (long long));
    
    for (unsigned long long i = 2; i <= n; ++i)
        phi[i] = i - 1;
    
    for (unsigned long long i = 2; i <= n; ++i) {
        for (unsigned long long j = (i << 1); j <= n; j += i)
            phi[j] -= phi[i];
        res += phi[i];
    }
    
    fo << (res << 1) + 1;
    free (phi);
    
    return 0;
}