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<iostream>
#include<cstring>
#include<cmath>
using namespace std;
char s1[205],s2[205];
int main()
{
    for(;;)
    {
        scanf("%s",s1);
        if(s1[0]=='.')break;
        scanf("%s",s2);
        int len1=strlen(s1);
        int len2=strlen(s2);
        int t1=0,t2=0;
        for(int i=0;i<len1;i++)if(s1[i]=='\"')t1++;
        for(int i=0;i<len2;i++)if(s2[i]=='\"')t2++;
        if(t1!=t2)cout<<"DIFFERENT"<<endl;
        else
        {
            int t1=0,t2=0;
            int flag=0,flag1=0;
            while(t1<len1&&t2<len2)
            {
                while(s1[t1]=='\"'&&t1<len1&&s2[t2]=='\"'&&t2<len2)
                    {
                        t1++;
                        t2++;
                        flag1++;
                    }
                if(t1==len1||t2==len2)break;
                if(flag1%2==0)
                {
                    if(s1[t1]!=s2[t2]){flag=2;break;}
                    while(s1[t1]!='\"'&&s2[t2]!='\"'&&t1<len1&&t2<len2)
                    {
                        if(s1[t1]!=s2[t2]){flag=2;break;}
                        else {t1++;t2++;}
                    }
                }
                else if(flag1%2!=0)
                {
                    while((s1[t1]!='\"'||s2[t2]!='\"')&&t1<len1&&t2<len2)
                    {
                        if(s1[t1]!=s2[t2])
                            {
                                flag++;
                                while(s1[t1]!='\"'&&t1<len1)t1++;
                                while(s2[t2]!='\"'&&t2<len2)t2++;
                                break;
                            }
                        else {t1++;t2++;}
                    }
                }
                if(flag==2)break;
            }
            if(flag==2)cout<<"DIFFERENT"<<endl;
            else if(flag==1)cout<<"CLOSE"<<endl;
            else if(flag==0)cout<<"IDENTICAL"<<endl;
        }
    }
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
using namespace std;
string s1, s2;

int main() {

  while (1) {
    int count = 0;
    int n1 = 0;
    int n2 = 0;
    int error = 0;

    cin >> s1;
    if(s1 == ".") break;
    cin >> s2;

    if(s1 == s2) {
      cout << "IDENTICAL" << endl;
      continue;
    }

    while(1) {
      if(s1[n1] == '"' && s2[n2] == '"') {
        n1++; n2++;
        count = 0;
        while(1) {
          if (s1[n1] == '"' && s2[n2] == '"') {
            if(count > 0) error++;
            break;
          }
          if (s1[n1] != s2[n2]) count++;
          if(s1[n1] != '"') n1++;
          if(s2[n2] != '"') n2++;
        }
      }
      else if(s1[n1] != s2[n2]) {
        cout << "DIFFERENT" << endl;
        break;
      }
      if(n1 != s1.size()) n1++;
      if(n2 != s2.size()) n2++;
      if(n1 == s1.size() && n2 == s2.size())  {
        if (error >= 2 ) {
          cout << "DIFFERENT" << endl;
          break;
        }
        else {
          cout << "CLOSE" << endl;
          break;
        }
      }
    }
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;

#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
//const ll mod = 1000000007;

int main() {
    //cout.precision(10);
    cin.tie(0);
    ios::sync_with_stdio(false);
    while(true) {
        string S;
        getline(cin, S);
        if(S == ".") break;
        string T;
        getline(cin, T);
        if(S == T) {
            cout << "IDENTICAL" << endl;
            continue;
        }
        vector<string> s, t;
        s.push_back("");
        t.push_back("");
        bool on = false;
        for(int i = 0; i < S.size(); i++) {
            if(S[i] != '"') {
                s.back().push_back(S[i]);
                continue;
            }
            s.push_back("");
            on = !on;
        }
        on = false;
        for(int i = 0; i < T.size(); i++) {
            if(T[i] != '"') {
                t.back().push_back(T[i]);
                continue;
            }
            t.push_back("");
            on = !on;
        }
        int diff = 0;
        /*
        for(int i = 0; i < s.size(); i++) {
            cerr << s[i] << " ";
        }
        cerr << endl;
        for(int i = 0; i < t.size(); i++) {
            cerr << t[i] << " ";
        }
        cerr << endl;
        */
        if(s.size() != t.size()) diff = 100;
        for(int i = 0; i < min(s.size(), t.size()); i++) {
            if(s[i] == t[i]) continue;
            //cerr << i << endl;
            if(i % 2 == 0) {
                //cerr << i << endl;
                diff = 100;
            }
            else diff++;
        }
        if(diff == 1) cout << "CLOSE" << endl;
        else cout << "DIFFERENT" << endl;
    }
    return 0;
}