import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        }
    } import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        }
    } Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        } main {
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int res = 0; res 0 res = (1000 - N%1000)%1000 res (1000 - N%1000)%1000 (1000 - N%1000) 1000 N%1000 N 1000 1000 System.out.println(res) System.out.println System.out System System.out res String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        }
    } public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        }
    } Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int res = 0;
        
        
        res = (1000 - N%1000)%1000; 
        
        System.out.println(res);
                
            
        
        
        
        
        
        }
    }