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<string>
using namespace std;

int main(){
 while(true){
  string s1, s2;
  cin >> s1;
  if(s1 == ".") break;
  cin >> s2;

  //?????¨??????????????´???
  if(s1 == s2){
   cout << "IDENTICAL" << endl;
   continue; //??\??????while?????????????????????????????????while??????????????????
  }

  //??????????????°????????´???
  string t1 = s1;
  string t2 = s2;

  while(true){
   size_t d1b = t1.find('\"'); //t1???"???????§???????
   if(d1b == string::npos) break;
   t1.replace(d1b, 1, "@");
   
   size_t d1e = t1.find('\"'); //t1???"???????????????
   t1.replace(d1e, 1, "@");

   size_t d2b = t2.find('\"'); //t2???"???????§???????
   if(d2b == string::npos) break;
   t2.replace(d2b, 1, "@");
   
   size_t d2e = t2.find('\"'); //t2???"???????????????
   t2.replace(d2e, 1, "@");

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

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

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

  //????????\???
  else{
   cout << "DIFFERENT" << endl;
  }
 }

 return 0;
}

C++: #include <bits/stdc++.h>

#define CEIL(a,b) ((a) / (b) + ((a) % (b) == 0 ? 0 : 1))

using namespace std;
using ll = long long;
using pii = pair<int, int>;

constexpr int MOD = 1'000'000'007;
constexpr int INF = 1'000'000'001;
constexpr ll LLINF = 4'000'000'000'000'000'001;
// constexpr int INF = 2147483647; // 2 * 1e9
// constexpr ll LLINF = 9223372036854775807; // 9 * 1e18

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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(10);
    while(true){
        string s, t;
        cin >> s;
        if(s == ".") break;
        cin >> t;
        int i = 0, j = 0, cnt = 0;
        while(i < s.size() && j < t.size()){
            if(s[i] != t[j]){
                cnt = 114514;
                break;
            }
            if(s[i] == '"'){
                ++i;
                ++j;
                while(i < s.size() && j < t.size()){
                    if(s[i] != t[j]){
                        ++cnt;
                        while(s[i] != '"'){++i;}
                        while(t[j] != '"'){++j;}
                        break;
                    }
                    if(s[i] == '"') break;
                    ++i;
                    ++j;
                }
            }
            ++i;
            ++j;
        }
        if(i != s.size() || j != t.size()) cnt = 114514;
        cout << (cnt == 0 ? "IDENTICAL" : cnt == 1 ? "CLOSE": "DIFFERENT") << "\n";
    }
    return 0;
}

C++: #include<string>
#include<iostream>
#include<vector>

using namespace std;

vector<string> split(const string& s, char delim) {
    int left = 0;
    auto v = vector<string>();
    for (int i = 0; i < s.size(); ++i) {
        if (s[i] == delim) {
            v.push_back(s.substr(left, i - left));
            left = i + 1;
        }
    }
    v.push_back(s.substr(left,s.size() - left));
    return v;
}

int main()
{
    while(1) {
        string s1, s2;
        cin >> s1 >> s2;
        if (s1 == ".") break;
        if (s1 == s2) { cout << "IDENTICAL" << endl; continue; }
        auto v1 = split(s1, '"');
        auto v2 = split(s2, '"');
        if (v1.size() != v2.size()) { cout << "DIFFERENT" << endl; continue; }
        int mis = 0; int cost = 2;
        for (int i = 0; i < v1.size(); ++i) {
            if (v1[i] != v2[i]) mis += cost;
            cost = cost == 2 ? 1 : 2;
        }
        cout << (mis > 1 ? "DIFFERENT" : "CLOSE") << endl;
    }
}