package com.company;
import java.io.*;
import java.nio.file.*;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.*;


public class Sync {
    static Path pathS;
    static Path pathD;
    static Set <Path> copyHashSet   = new HashSet<Path>();
    static Set <Path> deleteHashSet = new HashSet<Path>();

    static boolean FileComparator (File fileA, File fileB) throws IOException {
        if (fileA.length() != fileB.length()) return false;
        else {
            BufferedInputStream inA = new BufferedInputStream(new FileInputStream(fileA));
            BufferedInputStream inB = new BufferedInputStream(new FileInputStream(fileB));
            char cA, cB;
            while (inA.available() > 0  && inB.available() > 0) {
                cA = (char) inA.read();
                cB = (char) inB.read();
                if (cA != cB) return false;
            }
        }
        return true;
    }


    static class CopyingFileVisitor extends SimpleFileVisitor<Path>  {

        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attr) throws IOException {
            copyHashSet.add(file.subpath(1, file.getNameCount())); // adding path
            //System.out.println(file.getNameCount());     // getNameCount returns number of folders in current path (starting from S )
            return FileVisitResult.CONTINUE;
        }
    }

    static class DeletingFileVisitor extends SimpleFileVisitor <Path> {


        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attr) throws IOException {
            Path d = file.subpath(1, file.getNameCount());
            Path s = FileSystems.getDefault().getPath(pathS.toString() + "/" + d.toString());
            if (copyHashSet.contains(d) && FileComparator(s.toFile(), file.toFile())) copyHashSet.remove(d); // both files exist and equal
            else deleteHashSet.add(d); // both files exist but not equal or  file does exist in D but not in S
            return FileVisitResult.CONTINUE;
        }
    }

    public static void main(String[] args) throws IOException {
        // write your code here
        File S = new File(args[0]);
        File D = new File(args[1]);
        pathS = S.toPath();
        pathD = D.toPath();
        Files.walkFileTree(pathS, new CopyingFileVisitor());
        Files.walkFileTree(pathD, new DeletingFileVisitor());
        if (copyHashSet.isEmpty() && deleteHashSet.isEmpty()) {
            System.out.println("IDENTICAL");
        } else {
            ArrayList <Path> copyList = new ArrayList<Path>(copyHashSet);
            ArrayList <Path> deleteList = new ArrayList<Path>(deleteHashSet);
            Collections.sort(copyList);
            Collections.sort(deleteList);

            for (int i = 0; i < deleteList.size(); i++) {
                System.out.println("DELETE " + deleteList.get(i));
            }

            for (int i = 0; i < copyList.size(); i++) {
                System.out.println("COPY " + copyList.get(i));
            }
        }
    }
}