import java.awt.*;
import java.awt.geom.*;
import java.io.*;
import java.util.*;
class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		if(n == 1) {
			System.out.println(1);
		}
		else if(n == 0) {
			System.out.println(0);
		}
		else {
			System.out.println(n - 1);
		}
	} 	
}