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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <climits>
#include <vector>
#include <map>
#include <set>
#include <list>
#include <stack>
#include <queue>
#include <algorithm>
#include <iostream>
#include <string>

#define REP(i,n) for(long long i=0;i<n;++i)
#define REPR(i,n) for(long long i=n;i>=0;--i)
#define REPI(itr,v) for(auto itr=v.begin();itr!=v.end();++itr)
#define REPIR(itr,v) for(auto itr=v.rbegin();itr!=v.rend();++itr)
#define FOR(i,a,b) for(long long i=a;i<b;++i)
#define SORT(v,n) sort(v, v+n)
#define SORTV(v) sort(v.begin(), v.end())
#define ALL(v) v.begin(),v.end()
#define llong long long
#define INF 999999999
#define MOD 1000000007
#define pb push_back
#define pf push_front
#define MP make_pair
#define SV(v) {for(long long sitr=0;sitr<v.size();++sitr){cin>>v[sitr];}}

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

using namespace std;

typedef pair<int,int> pii;

int main(){

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

    cin >> s2;

    if(s1 == s2){
      cout << "IDENTICAL\n";
    }else{

      vector<string> c, d;
      int ii = 0;
      REP(i,s1.length()){
        if(s1[i] == '"'){
          c.pb(s1.substr(ii, i - ii));
          int j = i + 1;
          while(true){
            if(s1[j] == '"'){
              ii = j+1;
              i = j;
              break;
            }
            j++;
          }
        }
      }
      
      c.pb(s1.substr(ii, s1.length() - ii));

      ii = 0;
      REP(i,s2.length()){
        if(s2[i] == '"'){
          d.pb(s2.substr(ii, i - ii));
          int j = i + 1;
          while(true){
            if(s2[j] == '"'){
              ii = j+1;
              i = j;
              break;
            }
            j++;
          }
        }
      }
      d.pb(s2.substr(ii, s2.length() - ii));



      if(c.size() != d.size()){
        cout << "DIFFERENT\n";
        continue;
      }

      bool end = false;
      REP(i,c.size()){
        if(c[i] != d[i]){
          cout << "DIFFERENT\n";
          end = true;
          break;
        }
      }
      if(end) continue;


      vector<string> a, b;
      REP(i,s1.length()){
        if(s1[i] == '"'){
          int j = i + 1;
          while(true){
            if(s1[j] == '"'){
              if(j - i != 1){
                string tmp = s1.substr(i+1, j - i - 1);
                a.pb(tmp);
              }else{
                a.pb("");
              }
              break;
            }
            j++;
          }
          i = j;
        }
      }
      REP(i,s2.length()){
        if(s2[i] == '"'){
          int j = i + 1;
          while(true){
            if(s2[j] == '"'){
              if(j - i != 1){
                string tmp = s2.substr(i+1, j - i - 1);
                b.pb(tmp);
              }else{
                b.pb("");
              }
              break;
            }
            j++;
          }
          i = j;
        }
      }

      if(a.size() == b.size()){
        int cnt = 0;
        bool f = true;
        REP(i,a.size()){
          if(a[i] != b[i]){
            cnt++;
            if(cnt == 2){
              f = false;
              break;
            }
          }
        }

        if(f){
          cout << "CLOSE\n";
        }else{
          cout << "DIFFERENT\n";
        }
      }else{
        cout << "DIFFERENT\n";
      }


    }
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

#define int long long

signed main() {
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  string s1;
  while ( cin >> s1, s1 != "." ) {
    string s2;
    cin >> s2;
    vector<string> t1, t2;
    {
      string s = "";
      for ( int i = 0; i < (int)s1.size(); i++ ) {
	if ( s1[i] == '"' ) {
	  t1.emplace_back(s);
	  s = "";
	} else s += s1[i];	
      }
      t1.emplace_back(s);      
    }
    {
      string s = "";
      for ( int i = 0; i < (int)s2.size(); i++ ) {
	if ( s2[i] == '"' ) {
	  t2.emplace_back(s);
	  s = "";	    
	} else s += s2[i];	
      }
      t2.emplace_back(s);      
    }

    if ( t1.size() != t2.size() ) {
      cout << "DIFFERENT" << endl;
      continue;
    }
    
    int cnt = 0;
    for ( int i = 0; i < (int)t1.size(); i++ ) {
      if ( i%2 ) {     
	if ( t1[i] != t2[i] ) cnt++;	
      } else {
	if ( t1[i] != t2[i] ) cnt += 2;
      }
    }
  
    if ( cnt == 0 ) cout << "IDENTICAL" << endl;
    else if ( cnt == 1 ) cout << "CLOSE" << endl;
    else cout << "DIFFERENT" << endl;    
  }
  
  return 0;
}