function iloczyn(x, y) {
  if (y == 1) {
    return x;
  } else {
    k = Math.floor(y / 2);
    z = iloczyn(x, k);
    if (y % 2 == 0) {
      return z + z;
    } else {
      return x + z + z;
    }
  }
}

console.log(iloczyn(9, 11));
console.log(iloczyn(9, 5));
console.log(iloczyn(9, 1));