Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		s := io.NextLine()
		if s == "." {
			break
		}
		t := io.NextLine()
		if s == t {
			io.Println("IDENTICAL")
			continue
		}
		ss := strings.Split(s, "\"")
		tt := strings.Split(t, "\"")
		if len(ss) != len(tt) {
			io.Println("DIFFERENT")
			continue
		}
		cnt := 0
		for i := 0; i < len(ss); i++ {
			if i%2 == 0 {
				if ss[i] != tt[i] {
					cnt = -1
					break
				}
			} else {
				if ss[i] != tt[i] {
					cnt++
				}
			}
		}
		if cnt > 1 || cnt == -1 {
			io.Println("DIFFERENT")
		} else {
			io.Println("CLOSE")
		}
	}
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static System.Console;
using static System.Math;

namespace AtTest.HCPC2019_15
{
    class C
    {
        static void Main(string[] args)
        {
            Method(args);
        }

        static void Method(string[] args)
        {
            string s1=Read();
            string s2;
            List<int> res = new List<int>();
            while (s1[0] != '.')
            {
                s2 = Read();
                string[] s1s = s1.Split('\"');
                string[] s2s = s2.Split('\"');
                if (s1s.Length != s2s.Length)
                {
                    res.Add(2);
                }
                else
                {
                    int comDifCnt = 0;
                    int litelDifCnt = 0;
                    for(int i =0; i < s1s.Length; i++)
                    {
                        if (!s1s[i].Equals(s2s[i]))
                        {
                            if (i % 2 == 0) comDifCnt++;
                            else litelDifCnt++;
                        }
                    }

                    if (comDifCnt == 0 && litelDifCnt == 0) res.Add(0);
                    else if (comDifCnt == 0 && litelDifCnt == 1) res.Add(1);
                    else res.Add(2);
                }
                s1 = Read();
            }


            for(int i =0; i < res.Count; i++)
            {
                switch (res[i])
                {
                    case 0:
                        WriteLine("IDENTICAL");
                        break;
                    case 1:
                        WriteLine("CLOSE");
                        break;
                    case 2:
                        WriteLine("DIFFERENT");
                        break;
                }
            }
        }

        private static string Read() { return ReadLine(); }
        private static char[] ReadChars() { return Array.ConvertAll(Read().Split(), a => a[0]); }
        private static int ReadInt() { return int.Parse(Read()); }
        private static long ReadLong() { return long.Parse(Read()); }
        private static double ReadDouble() { return double.Parse(Read()); }
        private static int[] ReadInts() { return Array.ConvertAll(Read().Split(), int.Parse); }
        private static long[] ReadLongs() { return Array.ConvertAll(Read().Split(), long.Parse); }
        private static double[] ReadDoubles() { return Array.ConvertAll(Read().Split(), double.Parse); }
    }
}

C++: #include <iostream>
#include <string>
using namespace std;


int main(){

	while(true){
		string s1;
		cin>>s1;

		if(s1==".")
			break;
		string s2;
		cin>>s2;

		if(s1==s2){
			cout<<"IDENTICAL"<<endl;
			continue;
		}

		string t1=s1;
		string t2=s2;

		while(true){

			size_t d1b =t1.find('\"');
			if(d1b==string::npos)
				break;
			t1.replace(d1b,1,"@");

			size_t d1e =t1.find('\"');
			t1.replace(d1e,1,"@");

			size_t d2b =t2.find('\"');
			if(d2b==string::npos)
				break;
			t2.replace(d2b,1,"@");

			size_t d2e =t2.find('\"');
			t2.replace(d2e,1,"@");

			string u1=s1;
			u1.replace(d1b+1,d1e-d1b-1,"");

			string u2=s2;
			u1.replace(d2b+1,d2e-d2b-1,"");

			if(u1==u2){
				t1=u1;
				t2=u2;
				break;
			}
		}

		if(t1==t2){
			cout<<"CLOSE"<<endl;
		}else{
			cout<<"DIFFERENT"<<endl;
		}
	}
	return 0;
}

C++: // 2017/12/11 Tazoe

#include <iostream>
#include <string>
using namespace std;

int main()
{
	while(true){
		string s1;
		cin >> s1;

		if(s1==".")
			break;

		string s2;
		cin >> s2;

		if(s1==s2){
			cout << "IDENTICAL" << endl;
			continue;
		}

		string t1 = s1;
		string t2 = s2;

		while(true){
			size_t d1b = t1.find('\"');
			if(d1b==string::npos)
				break;
			t1.replace(d1b, 1, "@");

			size_t d1e = t1.find('\"');
			t1.replace(d1e, 1, "@");

			size_t d2b = t2.find('\"');
			if(d2b==string::npos)
				break;
			t2.replace(d2b, 1, "@");

			size_t d2e = t2.find('\"');
			t2.replace(d2e, 1, "@");

			string u1 = s1;
			u1.replace(d1b+1, d1e-d1b-1, "");
			string u2 = s2;
			u2.replace(d2b+1, d2e-d2b-1, "");

//			cout << u1 << endl;
//			cout << u2 << endl;

			if(u1==u2){
				t1 = u1;
				t2 = u2;
				break;
			}
		}

		if(t1==t2){
			cout << "CLOSE" << endl;
		}
		else{
			cout << "DIFFERENT" << endl;
		}
	}

	return 0;
}