def steps_to_miles(steps):
    """Convert steps to miles."""
    if steps < 0:
        raise ValueError("Exception: Negative step count entered.")
    return steps / 2000

if __name__ == '__main__':
    try:
        # Read number of steps from user
        steps = int(input())
        # Convert steps to miles
        miles = steps_to_miles(steps)
        # Output the result with 2 decimal places
        print(f'{miles:.2f}')
    except ValueError as e:
        # Handle both the negative step exception and invalid integer input
        print(str(e))