/*
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 */
package aer515;

import java.util.Scanner;

/**
 *
 * @author Usuario
 */
public class AER515 {

    Scanner in;

    /**
     * @param args the command line arguments
     */
    public boolean caso() {
        int casos = Integer.parseInt(in.nextLine());

        if (casos == 0) {
            return false;
        }
        if(casos == 1){
            System.out.println(casos);
        }else if (casos % 2 == 0) {
            System.out.println(casos - 1);
        } else {
            int resultado;
            resultado = casos - (casos * 1) / 2;

            System.out.println(resultado);
        }

        return true;
    }

    public void run() {
        in = new Scanner(System.in);

        while (caso()) {

        }
    }

    public static void main(String[] args) {
        new AER515().run();
        // TODO code application logic here
    }

}