def is_power_of_two(n):
    # Check if n is positive and a power of two using bitwise operation
    return n > 0 and (n & (n - 1)) == 0

# Example usage
print(is_power_of_two(1))   # Output: True
print(is_power_of_two(16))  # Output: True
print(is_power_of_two(3))   # Output: False