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 <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define len(v) (int)(v).size()

using namespace std;

int main()
{
    while(1){
        string s,t;
        cin >> s;
        if(s == ".") break;
        cin >> t;
        if(s == t){
            cout << "IDENTICAL\n";
            continue;
        }
        vector<string> a[2];
        vector<string> b[2];
        int st = -1, nw = 0;
        s.push_back('\"');
        rep(i,len(s)){
            if(s[i] == '\"'){
                a[nw].push_back(s.substr(st+1,i-st-1));
                st = i;
                nw ^= 1;
            }
        }
        st = -1, nw = 0;
        t.push_back('\"');
        rep(i,len(t)){
            if(t[i] == '\"'){
                b[nw].push_back(t.substr(st+1,i-st-1));
                st = i;
                nw ^= 1;
            }
        }
        if(a[0] != b[0]){
            cout << "DIFFERENT\n";
            continue;
        }
        if(len(a[1]) != len(b[1])){
            cout << "DIFFERENT\n";
            continue;
        }
        int dif = 0;
        rep(i,len(a[1])){
            if(a[1][i] != b[1][i]){
                if(dif){
                    cout << "DIFFERENT\n";
                    dif++;
                    break;
                }else{
                    dif++;
                }
            }
        }
        if(dif <= 1) cout << "CLOSE\n";
    }
}

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

using namespace std;

int main(){

  char s1[200]={0};
  char s2[200]={0};
  int c;
  cin>>s1>>s2;
 
  
  for(int i=0;i<200;i++){
    if(s1[i]!=s2[i]){
      c++;
    }
  }
    if(c==0){
      cout<<"IDENTICAL"<<endl;
    }else if(c==1){
      cout<<"CLOSE"<<endl;
    }else{
      cout<<"DIFFERENT"<<endl;
    }

return 0;
}

C++: #include<iostream>

using namespace std;

int main(){

  char s1[200]={0};
  char s2[200]={0};
  char t1[200]={0};
  char t2[200]={0};
  char u1[200]={0};
  char u2[200]={0};

  int c=0,flag=0,j=0,k=0,l=0;
  for(int x=0;x<100;x++){
  cin>>s1;
  if(s1[0]=='.') break;
  cin>>s2;
  for(int i=0;i<200;i++){
    if(s1[i]=='"'){
      if(flag==0){
	flag=1;
	
      }else if(flag==1){
	flag=0;
	
      }
    }

    if(flag==1){
      t1[j]=s1[i];
      j++;    
    }

    if(flag==0){
      u1[l]=s1[i];
      l++;    
    }


  }
  j=0;
  l=0;
 for(int i=0;i<200;i++){

    if(s2[i]=='"'){
      if(flag==0){
	flag=1;
	
      }else if(flag==1){
	flag=0;
	
      }
    }

    if(flag==1){
      t2[j]=s2[i];
      j++;
    }

 if(flag==0){
      u2[l]=s2[i];
      l++;
    }

  }
 j=0;
 flag=0;

 /* cout<<t1<<endl;
 cout<<t2<<endl;
 cout<<u1<<endl;
 cout<<u2<<endl;*/

 //kyuukei~~~

   
  for(int i=0;i<150;i++){


    if(flag==1){
    if(t1[j]!=t2[k]){
      c++;
      flag=0;
    }

    if(t1[j]=='"' && t2[k]!='"'){
      j--;
    }
    if(t2[k]=='"' && t1[j]!='"'){
      k--;
    }

    j++;
    k++;

    }

   if(t1[j]=='"' && t2[k]=='"'){
     flag=1;

    }


  }

  for(int i=0;i<200;i++){
    if(u1[i]!=u2[i]){
      c=2;
    }
  }

    if(c==0){
      cout<<"IDENTICAL"<<endl;
    }else if(c==1){
      cout<<"CLOSE"<<endl;
    }else{
      cout<<"DIFFERENT"<<endl;
    }
  }

return 0;
}

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

bool close(string s1,string s2){
    bool in_db_quo=false;
    int index1=0;
    int index2=0;
    int times=0;//一致していない二重引用符
    int l_of_sen1=s1.length(),l_of_sen2=s2.length();
    while(true){
        if(!in_db_quo){
           if(s1[index1]=='"' && s2[index2]=='"')in_db_quo=true;
           if(!(s1[index1] == s2[index2]))return false;//different
        }
        else{
           int index1_s=index1,index2_s=index2;//二重引用符の中の始まりの添字
           bool end_quo1=false,end_quo2=false;//終わりの方の二重引用符にいるかを表す
           while(!end_quo1 || !end_quo2){
               if(!end_quo1){
                   if(s1[index1] == '"')end_quo1 = true;
                   if(!end_quo1)index1++;
               }
               if(!end_quo2){
                   if(s2[index2] == '"')end_quo2 = true;
                   if(!end_quo2)index2++;
               }
           }
           if(!(s1.substr(index1_s,index1-index1_s) == s2.substr(index2_s,index2-index2_s))){
               times++;
               if(times>=2)return false;//different
           }
           in_db_quo=false;
        }
        if(index1==l_of_sen1-1 || index2==l_of_sen2-1){
             if(index1==l_of_sen1-1 && index2==l_of_sen2-1)return true;
             else return false;
        }
        index1++;index2++;
    }
}
int main(){
    string s1,s2;
    while(true){
        cin>>s1;
        if(s1==".")break;
        cin>>s2;
        if(s1==s2)cout<<"IDENTICAL"<<endl;
        else if(close(s1,s2))cout<<"CLOSE"<<endl;
        else cout<<"DIFFERENT"<<endl;
    }
}