import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;


public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    }

    public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    }

    private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.Arrays; Arrays java.util public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    }

    public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    }

    private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    }
} Main public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    } main {
        Main main = new Main();
        main.solve(args);
    } Main main = new Main(); main new Main() main.solve(args) main.solve main args String[] args args public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    } solve {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    } MyScanner scanner = new MyScanner(); scanner new MyScanner() int n = Integer.parseInt(scanner.next()); n Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner int ans = 0; ans 0 if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		} n % 1000 != 0 n % 1000 n 1000 0 {
			ans = 1000 - n % 1000;
		} ans = 1000 - n % 1000 ans 1000 - n % 1000 1000 n % 1000 n 1000 {
			ans = 0;
		} ans = 0 ans 0 System.out.println(ans) System.out.println System.out System System.out ans String[] args args private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    } MyScanner String[] s; s int i; i BufferedReader br; br String reg = " "; reg " " MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        } MyScanner {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        } s = new String[0] s new String[0] 0 i = 0 i 0 br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        } next {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        } try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();} Exception e {e.printStackTrace();} e.printStackTrace() e.printStackTrace e {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } if (i < s.length) return s[i++]; i < s.length i s.length s s.length return s[i++]; s[i++] s i++ i String line = br.readLine(); line br.readLine() br.readLine br while (line.equals("")) {line = br.readLine();} line.equals("") line.equals line "" {line = br.readLine();} line = br.readLine() line br.readLine() br.readLine br s = line.split(reg, 0) s line.split(reg, 0) line.split line reg 0 i = 0 i 0 return s[i++]; s[i++] s i++ i return null; null public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } nextInt {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();} Exception e {e.printStackTrace();} e.printStackTrace() e.printStackTrace e {return Integer.parseInt(next());} return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next return -1; -1 1 public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } nextDouble {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();} Exception e {e.printStackTrace();} e.printStackTrace() e.printStackTrace e {return Double.parseDouble(next());} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next return -1; -1 1 public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } nextLong {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        } try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();} Exception e {e.printStackTrace();} e.printStackTrace() e.printStackTrace e {return Long.parseLong(next());} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next return -1; -1 1 public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    }

    public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    }

    private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    }
} public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    }

    public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    }

    private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;


public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.solve(args);
    }

    public void solve(String[] args) {
        MyScanner scanner = new MyScanner();

        // ビジネスロジックここから
        int n = Integer.parseInt(scanner.next());
        int ans = 0;
		if(n % 1000 != 0) {
			ans = 1000 - n % 1000;
		} else {
			ans = 0;
		}
        System.out.println(ans);
        
        // ビジネスロジックここまで

    }

    private class MyScanner {
        String[] s;
        int i;
        BufferedReader br;
        String reg = " ";
        MyScanner () {
            s = new String[0];
            i = 0;
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        public String next() {
            try {
                if (i < s.length) return s[i++];
                String line = br.readLine();
                while (line.equals("")) {line = br.readLine();}
                s = line.split(reg, 0);
                i = 0;return s[i++];
            } catch (Exception e) {e.printStackTrace();}
            return null;
        }
        public int nextInt() {
            try {return Integer.parseInt(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public double nextDouble() {
            try {return Double.parseDouble(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
        public long nextLong()  {
            try {return Long.parseLong(next());} catch (Exception e) {e.printStackTrace();}
            return -1;
        }
    }
}
