uva 10820 send a table

using namespace std;

const int MAX_N = 50000;

int N;
int phi[MAX_N + 1];

void (int N) {
  for (int i = 1; i <= N; i++) phi[i] = i;
  for (int i = 2; i <= N; i++) {
    
    if (phi[i] != i) continue;
    for (int j = i; j <= N; j += i) {
      // first / i then * (i - 1)
      // ensures phi[j] <= j and no overflow
      phi[j] = phi[j] / i * (i - 1);
    }
  }
}

int main() {
  euler_function(MAX_N);

  while (scanf("%d", &N) && N) {
    int res = 0;
    for (int i = 1; i <= N; i++) res += phi[i];
    res = res * 2 - 1;

    printf("%dn", res);
  }

  return 0;
}