import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int left = sc.nextInt();
        int right = sc.nextInt();
        int c = sc.nextInt() % 1000;
        int mod = (left - 1) % 1000 * c % 1000;
        boolean[] visited = new boolean[1000];
        for (int i = left; i <= right; i++) {
            mod = (mod + c) % 1000;
            if (visited[mod]) {
                break;
            } else {
                visited[mod] = true;
            }
        }
        int ans = 0;
        if (!visited[0]) {
            for (int i = 999; i > 0; i--) {
                if (visited[i]) {
                    ans = 1000 - i;
                    break;
                }
            }
        }
        System.out.println(ans);
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}