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++: #include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
#define chmin(a, b) ((a)=min((a), (b)))
#define chmax(a, b) ((a)=max((a), (b)))
#define fs first
#define sc second
#define eb emplace_back
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef tuple<int, int, int> T;

const ll MOD=1e9+7;
const ll INF=1e18;
const double pi=acos(-1);
const double eps=1e-10;

int dx[]={1, 0, -1, 0};
int dy[]={0, -1, 0, 1};

int main(){
    while(1){
        string s1; cin>>s1;
        if(s1 == ".") return 0;
        string s2; cin>>s2;

        if(s1 == s2){
            cout << "IDENTICAL" << endl;
            continue;
        }
        
        int cnt = 1;
        vector<string> ans1, ans2;
        vector<string> ans3, ans4;
        int h = 0;
        for(int i=0; i<s1.size(); i++){
            if(cnt % 2 == 1 && s1[i] == '\"'){
                string s3 = s1.substr(h, i - h + 1);
                ans3.eb(s3);
                h = i;
                cnt++;
            }
            else if(cnt % 2 == 0 && s1[i] == '\"'){
                string s3 = s1.substr(h, i - h + 1);
                cnt++;
                if(s3 == "") ans1.eb("?");
                else ans1.eb(s3);
                h = i;
            }

            if(i == s1.size() - 1){
                if(cnt % 2){
                    string s3 = s1.substr(h, i - h + 1);
                    ans3.eb(s3);
                }
                else{
                    string s3 = s1.substr(h, i - h + 1);
                    ans1.eb(s3);
                }
            }
        }

        cnt = 1;
        h = 0;
        for(int i=0; i<s2.size(); i++){
            if(cnt % 2 && s2[i] == '\"'){
                string s3 = s2.substr(h, i - h + 1);
                ans4.eb(s3);
                h = i;
                cnt++;
            }
            else if(cnt % 2 == 0 && s2[i] == '\"'){
                cnt++;
                string s3 = s2.substr(h, i - h + 1);
                h = i;
                if(s3 == "") ans2.eb("?");
                else ans2.eb(s3);
            }

            if(i == s2.size() - 1){
                if(cnt % 2){
                    string s3 = s2.substr(h, i - h + 1);
                    ans4.eb(s3);
                }
                else{
                    string s3 = s2.substr(h, i - h + 1);
                    ans2.eb(s3);
                }
            }
        }

        bool valid = true;
        for(int i=0; i<ans3.size() && i<ans4.size(); i++){
            if(ans3[i] != ans4[i] && valid){
                //cout << ans3[i] << " " << ans4[i] << endl;
                cout << "DIFFERENT" << endl;
                valid = false;
            }
        }

        int dif = 0;
        for(int i=0; i<ans1.size() && i<ans2.size(); i++){
            if(ans1[i] != ans2[i]) dif++;
        }

        if(valid){
            if(dif == 1) cout << "CLOSE" << endl;
            else cout << "DIFFERENT" << endl;
        }
    }
}

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;
      u2.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++: #include <iostream>
#include "string"

using namespace std;


int main(){
	while(1){
		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 (1) {
			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;
			t1.replace(d2b,1,"@");

			size_t d2e=t2.find('\"');
			t1.replace(d2e,1,"@");

			string u1=s1;
			u1.replace(d1b+1,d1e-d1b-1,"");
			string u2=s2;
			u2.replace(d2b+2,d2e-d2b-2,"");

			if (u1==u2) {
				t1=u1;
				t2=u2;
				break;
			}
		}
		if(t1==t2) cout<<"CLOSE"<<endl;
		else cout<<"DIFFERENT"<<endl;
	}
	return 0;
}