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 <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>
#include <cstring>

#define rep(i, m, n) for(int i=int(m);i<int(n);i++)
#define all(c) begin(c),end(c)

template<typename T1, typename T2>
inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }

template<typename T1, typename T2>
inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }

//改造
typedef long long int ll;
using ll = long long int;
using ull = long long unsigned int;
using namespace std;
#define INF (1 << 30) - 1
#define INFl (ll)5e15
#define DEBUG 0 //デバッグする時1にしてね
#define dump(x)  cerr << #x << " = " << (x) << endl
#define MOD 1000000007


//ここから編集する
class Solve {
public:
    vector<string> split(string s) {
        string tmp;
        vector<string> ret;
        for (int i = 0; i < s.size(); ++i) {
            if (i + 1 == s.size()) {
                if (s[i] == '\"') {
                    ret.push_back(tmp);
                    tmp = "";
                } else {
                    tmp += s[i];
                    ret.push_back(tmp);
                }
            }
            if (s[i] == '\"') {
                ret.push_back(tmp);
                tmp = "";
            } else {
                tmp += s[i];
            }
        }
        return ret;
    }

    bool solve() {
        string s1, s2;
        cin >> s1;
        if (s1 == ".") return false;
        cin >> s2;
        if (s1 == s2) {
            cout << "IDENTICAL" << endl;
            return true;
        }

        auto ss1 = split(s1);
        auto ss2 = split(s2);
        if (ss1.size() != ss2.size()) {
            cout << "DIFFERENT" << endl;
            return true;
        }

        int cnt = 0;
        for (int i = 0; i < ss1.size(); ++i) {
            if (i % 2 == 0) {
                if (ss1[i] != ss2[i]) {
                    cout << "DIFFERENT" << endl;
                    return true;
                }
            } else {
                if (ss1[i] != ss2[i]) {
                    cnt++;
                }
            }
        }
        if (cnt > 1) {
            cout << "DIFFERENT" << endl;
            return true;
        } else {
            cout << "CLOSE" << endl;
            return true;
        }


        return true;
    }
};


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    while (Solve().solve());

    return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;
 
int main()
{
    while(true){
        string s1;
        cin >> s1;
 
        if(s1==".")
            break;
 
        string s2;
        cin >> s2;
 
        if(s1==s2){
            cout << "IDENTICAL" << endl;
            continue;
        }
 
        string t1 = s1;
        string t2 = s2;
 
        while(true){
            size_t d1b = t1.find('\"');
            if(d1b==string::npos)
                break;
            t1.replace(d1b, 1, "@");
 
            size_t d1e = t1.find('\"');
            t1.replace(d1e, 1, "@");
 
            size_t d2b = t2.find('\"');
            if(d2b==string::npos)
                break;
            t2.replace(d2b, 1, "@");
 
            size_t d2e = t2.find('\"');
            t2.replace(d2e, 1, "@");
 
            string u1 = s1;
            u1.replace(d1b+1, d1e-d1b-1, "");
            string u2 = s2;
            u2.replace(d2b+1, d2e-d2b-1, "");
 
            if(u1==u2){
                t1 = u1;
                t2 = u2;
                break;
            }
        }
         if(t1==t2){
            cout << "CLOSE" << endl;
        }
        else{
            cout << "DIFFERENT" << endl;
        }
    }
 
    return 0;
}