CountOfEqualBitPairs

import java.util.Scanner;


public class CountOfEqualBitPairs {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        int number = input.nextInt();
        int zeroCount = 0;
        int oneCount = 0;
        int pairs = 0;

        while (number != 0) {
            int digit = number % 2;

            if (digit == 0) {
                zeroCount++;

                if (zeroCount >= 2) {
                    pairs++;
                    zeroCount--;
                }

                oneCount = 0;
            }

            else if (digit == 1) {
                oneCount++;

                if (oneCount >= 2) {
                    pairs++;
                    oneCount--;
                }

                zeroCount = 0;
            }

            number /= 2;
        }

        System.out.println(pairs);

        input.close();

    }

}