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>
#include <vector>

using namespace std;

int main()
{
  while(1){
    string row1,row2;
    string period(".");
    string cover("\"");

    cin>>row1;
    if(row1 == period){
      break;
    }
    cin>>row2;

    if(row1 == row2){
      cout<<"IDENTICAL"<<endl;
    }
    else{
      int size1 = row1.size();
      vector<string> Row1;
      int j = 0;
      string temp2;

      for(int i = 0;i < size1;++i){ 
        string temp1;
        temp1 = row1[i];
        if(temp1 == cover){
          string temp4;
          Row1.push_back(temp2);
          temp2 = temp4;
        }
        else if(i == size1 - 1){
          temp2 += temp1;
          Row1.push_back(temp2);
        }
        else{
          temp2 += temp1;
        }
      }

      int size2 = row2.size();
      vector<string> Row2;
      string temp3;

      for(int i = 0;i < size2;++i){ 
        string temp1;
        temp1 = row2[i];
        if(temp1 == cover){
          string temp4;
          Row2.push_back(temp3);
          temp3 = temp4;
        }
        else if(i == size2 - 1){
          temp3 += temp1;
          Row2.push_back(temp3);
        }
        else{
          temp3 += temp1;
        }
      }

      int Size1 = Row1.size();
      int Size2 = Row2.size();
      int count = 0;

      /*if(Size1 != Size2){
        cout<<"DIFFERENT"<<endl;
      }*/
      //else{
        for(int i = 0;i < Size1;++i){
          string check1,check2;
          check1 = Row1[i];
          check2 = Row2[i];
          int csize1 = check1.size();
          int csize2 = check2.size();

          if(i % 2 == 0){
            if(csize1 - csize2 >= 2 || csize2 - csize1 >= 2){
              cout<<"DIFFERENT"<<endl;
            }
            else if(csize1 - csize2 >= 1){
              ++count;
              for(int j = 0;j < csize2;++j){
                if(check1[j] != check2[j]){
                  ++count;
                }
              }
            }
            else if(csize2 - csize1 >= 1){
              ++count;
              for(int j = 0;j < csize1;++j){
                if(check1[j] != check2[j]){
                  ++count;
                }
              }
            }
            else{
              for(int j = 0;j < csize1;++j){
                if(check1[j] != check2[j]){
                  ++count;
                }
              }
            }
          }
          else{
            if(check1 != check2){
              ++count;
            }
          }

          if(count >= 2){
            cout<<"DIFFERENT"<<endl;
            break;
          }
        }
     // }

      if(count == 1){
        cout<<"CLOSE"<<endl;
      }
    }
  }
  
  return 0;
}

C++: #include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<array>
#include<map>
#include<iomanip>
#include<assert.h>
#include<bitset>
#include<stack>
#include<memory>
using namespace std;
using namespace std::chrono;
typedef long long int llint;
typedef double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
/*cout<<fixed<<setprecision(20);cin.tie(0);ios::sync_with_stdio(false);*/
const llint mod=998244353;
const llint big=2.19e15+1;
const long double pai=3.141592653589793238462643383279502884197;
const long double eps=1e-15;
template <class T,class U>bool mineq(T& a,U b){if(a>b){a=b;return true;}return false;}
template <class T,class U>bool maxeq(T& a,U b){if(a<b){a=b;return true;}return false;}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){if(a==0){return b;}return a/gcd(a,b)*b;}
template<class T> void SO(T& ve){sort(ve.begin(),ve.end());}
template<class T> void REV(T& ve){reverse(ve.begin(),ve.end());}
template<class T>llint LBI(vector<T>&ar,T in){return lower_bound(ar.begin(),ar.end(),in)-ar.begin();}
template<class T>llint UBI(vector<T>&ar,T in){return upper_bound(ar.begin(),ar.end(),in)-ar.begin();}
//  10:00-
//A 10:05 AC
int solve(void){
	string S,T;cin>>S;
	int i;
	if(S=="."){return 0;}
	cin>>T;
	if(S==T){cout<<"IDENTICAL"<<endl;return 1;}
	vector<string>Saa(1);
	vector<string>Taa(1);
	int bas=0;
	for(auto it:S){
		if(it=='"'){
			if(bas%2==0){Saa[0].pub('#');Saa.pub(string());}
			bas++;
		}else{
			if(bas%2==0){Saa[0].pub(it);}
			else{Saa[bas/2+1].pub(it);}
		}
	}
	bas=0;
	for(auto it:T){
		if(it=='"'){
			if(bas%2==0){Taa[0].pub('#');Taa.pub(string());}
			bas++;
		}else{
			if(bas%2==0){Taa[0].pub(it);}
			else{Taa[bas/2+1].pub(it);}
		}
	}
	if(Saa[0]!=Taa[0]||Saa.size()!=Taa.size()){cout<<"DIFFERENT"<<endl;return 1;}
	int tiga=0;
	for(i=1;i<Saa.size();i++){
		if(Saa[i]!=Taa[i]){tiga++;}
	}
	if(tiga<=1){cout<<"CLOSE"<<endl;}
	else{cout<<"DIFFERENT"<<endl;return 1;}
	return 1;
}
int main(void){
	while(solve()){}
}