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 range(i,a,b) for(long long i = (a); i < (b); i++)
#define rep(i,b) for(long long i = 0; i < (b); i++)
#define all(a) (a).begin(), (a).end()
#define show(x)  cerr << #x << " = " << (x) << endl;
using namespace std;
 
template <typename X, typename T>
auto vectors(X x, T a) {
	return vector<T>(x, a);
}
template <typename X, typename Y, typename Z, typename... Zs>
auto vectors(X x, Y y, Z z, Zs... zs) {
	auto cont = vectors(y, z, zs...);
	return vector<decltype(cont)>(x, cont);
}
template<typename T>
ostream& operator << (ostream& os, vector<T>& v){
	rep(i,v.size()){ os << v[i] << (i == v.size() - 1 ? "" : " "); } return os;
}
template<typename T>
istream& operator >> (istream& is, vector<T>& v){
	for(T& x: v){ is >> x; } return is;
}

vector<string> getWord(string& s){
	vector<string> res;
	res.emplace_back("a");

	string u;
	rep(i,s.size()){
		u += s[i];
		if(s[i] == '"'){
			i++;
			string t = "a";
			while(s[i] != '"'){
				t += s[i++];
			}
			res.emplace_back(t);
		}
	}
	s = u;
	return res;
}

int main(){
	string s, t;
	while(cin >> s, s[0] != '.'){
		cin >> t;

		if(s == t){
			cout << "IDENTICAL" << endl;
			continue;
		}

		auto a = getWord(s), b = getWord(t);
		if(a.size() != b.size() or s != t){
			cout << "DIFFERENT" << endl;
			continue;
		}

		int diff = 0;
		rep(i,a.size()){
			diff += a[i] != b[i];
		}

		if(diff == 1){
			cout << "CLOSE" << endl;
		}else{
			cout << "DIFFERENT" << endl;
		}
	}
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ll long long



int main(){
    while(true){
        string a,b;
        ll flaga=0,flagb=0,flagc=0;
        cin >> a;
        if(a == "."){
            return 0;
        }
        cin >> b;
        long unsigned int i=0,j=0;
        while(i != a.length() && j != b.length()){
            if(a[i]!=b[j]){
                if(flaga==0){
                    flagc=1;
                    break;
                }
                else if(flagb==1){
                    flagc=1;
                    break;
                }
                else{
                    flagb=1;
                    flagc=2;
                    while(a[i]!='"'){
                        i++;
                    }
                    while(b[j]!='"'){
                        j++;
                    }
                }
            }
            if(a[i]=='"'){
                if(flaga==0)flaga=1;
                else flaga=0;
            }
            i++;j++;
        }
        if(i != a.length() || j != b.length()){
            flagc=1;
        }
        if(flagc==1){
            cout << "DIFFERENT" << endl;
        }else if(flagc==2){
            cout << "CLOSE" << endl;
        }else{
            cout << "IDENTICAL" << endl;
        }
    } 
}

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;
        }
    }
}