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, N) for(ll i=(n); i<(N); i++)
#define RREP(i, n, N) for(ll i=(N-1); i>=n; i--)
#define SPACEREP(lst,itr) for(auto itr=lst.begin(); itr!=lst.end();++itr){cout<<*itr<<(++itr!=anslist.end()?" ":"\n");itr--;}
#define CK(n, a, b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define MCP(a, b) memcpy(b,a,sizeof(b))
#define p(s) cout<<(s)<<endl
#define p2(a, b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll mod = 1e9 + 7;
const ll inf = 1e18;

int main(){
    while(1){
        string s1,s2;
        cin >> s1;
        if(s1==".")break;
        cin >> s2;
        int miss=0,pos1=0,pos2=0;
        bool in_const=false;

        while((pos1!=s1.size()) || (pos2!=s2.size())){
            //もし一方が終わったら？
            if(pos1==s1.size() || pos2==s2.size()){
                miss=2;
                break;
            } 
            //普通の処理
            if(!in_const){//constじゃない
                if(s1[pos1]!=s2[pos2]){
                    miss=2;
                    break;
                }
                if(s1[pos1]=='"') in_const=true;
            }else{//const
                if(s1[pos1]!=s2[pos2]){
                    miss++;
                    while(s1[pos1]!='"'){
                        pos1++;
                    }
                    while(s2[pos2]!='"'){
                        pos2++;
                    }
                    in_const=false;
                }
                if(s1[pos1]=='"') in_const=false;
            }
            /**
            p(pos1);
            p(pos2);
            p(in_const);
            **/
            pos1++;
            pos2++;
        }

        if(miss==1){
            p("CLOSE");
        }else if (miss>1){
            p("DIFFERENT");
        }else{
            p("IDENTICAL");
        }
    }
}

C++: #include <algorithm>
#include <iostream>
#include <vector>
#include <math.h>
#include <set>
#include <map>
#include <string>
#include <stack>
#include <queue>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <bitset>
#include <complex>
#include <unistd.h>
#include <cassert>
#include <cctype>
#include <random>
#define _USE_MATH_DEFINES
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> plglg;
typedef tuple<int, int, int> tiii;
typedef tuple<ll, ll, ll> tlglglg;
typedef complex<double> xy_t;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
double pi = 3.141592653589793;
ll mod = 1000000007;
int intmax = 2147483647;
int intmin = -2147483648;
ll llmax = 9223372036854775807;
ll llmin = -9223372036854775807;
ll inf = llmax / 2;
double eps = 1e-11;

int main() {
    while (true) {
        string s1, s2;
        cin >> s1;
        if (s1 == ".") {
            break;
        }
        cin >> s2;
        vector<char> s1ch[200];
        vector<char> s2ch[200];
        int num1 = 0;
        for (int i = 0; i < s1.size(); i++) {
            if (s1[i] == '"') {
                num1++;
            } else {
                s1ch[num1].push_back(s1[i]);
            }
        }
        int num2 = 0;
        for (int i = 0; i < s2.size(); i++) {
            if (s2[i] == '"') {
                num2++;
            } else {
                s2ch[num2].push_back(s2[i]);
            }
        }
        int mark = 0;
        if (num1 != num2) {
            mark = 2;
        }
        for (int i = 0; i <= num1; i++) {
            bool m = true;
            int a = s1ch[i].size();
            int b = s2ch[i].size();
            if (a != b) {
                m = false;
            } else {
                for (int j = 0; j < a; j++) {
                    if (s1ch[i][j] != s2ch[i][j]) {
                        m = false;
                    }
                }
            }
            if (!m) {
                if (i % 2 == 0) {
                    mark = 2;
                } else {
                    if (mark < 2) {
                        mark++;
                    }
                }
            }
        }
        if (mark == 0) {
            cout << "IDENTICAL" << endl;
        } else if (mark == 1) {
            cout << "CLOSE" << endl;
        } else {
            cout << "DIFFERENT" << endl;
        }
    }
}

C++: while True:
    s1 = input()
    if s1 == '.':
        break
    s2 = input()

    if s1 == s2:
        print("IDENTICAL")
        continue

    s2 = s2.split('"')
    s1 = s1.split('"')
    # print(s1)
    # print(s2)
    count = 0
    isTmp = False
    if s1[0] == '"' and s2[0] == '"':
        isTmp = True

    for i in range(len(s1)):
        if len(s1) != len(s2):
            print("DIFFERENT")
            break
        if count > 1:
            print("DIFFERENT")
            break

        if not isTmp:
            if i % 2 == 0:
                if s1[i] != s2[i]:
                    print("DIFFERENT");
                    break
            if i % 2 == 1:
                if s1[i] != s2[i]:
                    count += 1
        else:
            if i+1 % 2 == 0:
                if s1[i] != s2[i]:
                    print("DIFFERENT");
                    break
            if i+1 % 2 == 1:
                if s1[i] != s2[i]:
                    count += 1

    if count == 1:
        print("CLOSE")