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("/"");
    string none("");

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

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

      for(int i = 0;i < size1;++i){ 
        string temp1;
        temp1 = row1[i];
        if(temp1 == cover){
          if(j == 0 && i != 0){
            Row1.push_back(temp2);
            j = 1;
          }
          else if((j == 0 && i == 0) || j == 1){
            Row1.push_back(none);
            j = 2;
          }
          else{
            Row1.push_back(none);
            j = 0;
          }
        }
        else if(i == size1 - 1){
          if(j == 0){
            temp2 += temp1;
            Row1.push_back(temp2);
          }
          else{
            temp2 = temp1;
            Row1.push_back(temp2);
          }
        }
        else{
          if(j == 1){
            temp2 = temp1;
            j = 0;
          }
          else{
            temp2 += temp1;
          }
        }
      }

      int size2 = row2.size();
      vector<string> Row2;
      string temp3;
      j = 0;

      for(int i = 0;i < size2;++i){ 
        string temp1;
        temp1 = row2[i];
        if(temp1 == cover){
          if(j == 0 && i != 0){
            Row2.push_back(temp3);
            j = 1;
          }
          else if((j == 0 && i == 0) || j == 1){
            Row2.push_back(none);
            j = 2;
          }
          else{
            Row2.push_back(none);
            j = 0;
          }
        }
        else if(i == size2 - 1){
          if(j == 0){
            temp3 += temp1;
            Row2.push_back(temp3);
          }
          else{
            temp3 = temp1;
            Row2.push_back(temp3);
          }
        }
        else{
          if(j == 1){
            temp3 = temp1;
            j = 0;
          }
          else{
            temp3 += temp1;
          }
        }
      }

      for(string e : Row1){
          cout<<e<<endl;
      }
      for(string e : Row2){
          cout<<e<<endl;
      }

      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];

          if(i % 2 == 0){
            if(check1 != check2){
              cout<<"DIFFERENT"<<endl;
              break;
            }
          }
          else{
            if(check1 != check2){
              ++count;
            }
          }
          
          if(count == 2){
            cout<<"DIFFERENT"<<endl;
            break;
          }
        }
      }

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

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

bool equal(string s1,string s2){
    if(s1==s2)return true;
    return false;
}

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(equal(s1,s2))cout<<"IDENTICAL"<<endl;
        else if(close(s1,s2))cout<<"CLOSE"<<endl;
        else cout<<"DIFFERENT"<<endl;
    }
}