$input int n;
$assume(n > 0);

int b[2 * n];

int main() {
  int a[n] = (int[n])$lambda(int i) 1;
 
  b = (int[2*n])$lambda(int i)(i%2==0 ? a[i/2] : b[i]);
  $assert($forall (int i | 0 <= i && i < 2*n && i%2 == 0) b[i] == 1);
  $assert($forall (int i | 0 <= i && i < 2*n && i%2 != 0) b[i] == 0);
}
