import java.util.*;     // needed for Scanner
public class WhileLoop {
   public static void main(String[] args) {
	   int numberOfThings, numberOfBits=0, temp;
	   Scanner inputScanner = new Scanner(System.in);
		System.out.println("Enter a number of things: ");
		numberOfThings = inputScanner.nextInt();
		temp = numberOfThings-1;
		while (temp>0) {  	// compute log base 2 of numberOfThings - 1 by
			temp = temp/2;    // repeated division
			numberOfBits++;
		}
		System.out.println("It requires " + numberOfBits + 
		   " bits to uniquely identify " + numberOfThings + " things");
	}
}