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>
using namespace std;

vector<string> make(string s)
{
    vector<string> v{""};
    for(char c:s)
    {
        if(c=='\"')
        {
            v.push_back("");
        }
        else
        {
            v.back()+=c;
        }
    }
    return v;
}

const string dif="DIFFERENT",ide="IDENTICAL",clo="CLOSE";

main()
{
    string s1,s2;
    while(cin>>s1>>s2)
    {
        if(s1==".") break;
        vector<string> v1=make(s1),v2=make(s2);
        if(v1.size()!=v2.size()) cout<<dif<<endl;
        else
        {
            int n=v1.size();
            int err=0;
            for(int i=0;i<n;i++)
            {
                if(v1[i]!=v2[i])
                {
                    if(~i&1) err++;
                    err++;
                }
            }
            if(err>1) cout<<dif<<endl;
            else if(err==1) cout<<clo<<endl;
            else cout<<ide<<endl;
        }
    }
}

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;
      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];

          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 <bits/stdc++.h>
using namespace std;

string s1, s2;

string solve() {
    s1 += '.';
    s2 += '.';
    int i = 0, j = 0;
    int qt1 = 0, qt2 = 0;
    int change = 0;
    while (i < s1.length() || j < s2.length()) {
        if (s1[i] == '"') qt1 = 1;
        if (s2[j] == '"') qt2 = 1;

        string t1 = "";
        if (qt1) {
            while (s1[++i] != '"') t1 += s1[i];
            qt1 = 0;
        }
        string t2 = "";
        if (qt2) {
            while (s2[++j] != '"') t2 += s2[j];
            qt2 = 0;
        }
        if (t1 != t2) {
          ++change;
        } else if (s1[i] != s2[j]) {
            return "DIFFERENT";
        }
        ++i;
        ++j;
    }
    if (change == 0) {
      return "IDENTICAL";
    } else if (change == 1) {
      return "CLOSE";
    } else {
      return "DIFFERENT";
    }
}

int main() {
    while (cin >> s1, s1[0] != '.') {
      cin >> s2;
      cout << solve() << endl;
    }
}