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<iostream>
#include<string>
#include<vector>

using namespace std;
typedef long long ll;

void split(string &s, vector<string> &v) {
	s += '"';
	string buf;
	for (int i = 0; i < s.size(); i++) {
		if (s[i] == '"') {
			v.push_back(buf);
			buf.clear();
		}
		else buf += s[i];
	}
}

int main() {

	while (1) {
		string S1, S2;
		cin >> S1;
		if (S1 == ".")break;
		cin >> S2;
		//すでに完全に一致ならば
		if (S1 == S2) {
			cout << "IDENTICAL" << endl;
			continue;
		}
		vector<string> v1, v2;
		split(S1, v1), split(S2, v2);

		if (v1.size() != v2.size()) {
			cout << "DIFFERENT" << endl;
			continue;
		}
		
		int cnt = 0;
		for (int i = 0; i < v1.size(); i++) {
			if (i % 2 == 1) {
				if (v1[i] != v2[i])cnt++;
			}
			else {
				if (v1[i] != v2[i]) {
					cout << "DIFFERENT" << endl;
					continue;
				}
			}
		}
		if (cnt == 1) {
			cout << "CLOSE" << endl;
		}
		else {
			cout << "DIFFERENT" << endl;
		}
	}
	
	return 0;
}

C++: #include <bits/stdc++.h>

#define MOD 1000000007
#define INF (0x7fffffff)
#define NINF (1<<31)
#define INFL (0x7fffffffffffffff)
#define NINFL (1LL<<63)
#define MAX 100000000

#define pe(str) return cout<<(str)<<endl,0
#define px(str) cout<<(str)<<endl,exit(0)
#define accu(ac,v) cout<<setprecision(ac)<<v<<endl
#define bpc(a) __builtin_popcount(a)
#define pr(str) cout<<(str)<<endl
#define prpr(str) cout<<str<<endl
#define db(str) cerr<<"debug:"<<(str)<<endl
#define dbdb(str) cerr<<"debugs:"<<str<<endl
#define re(i,n) for(int i=0;i<(n);i++)
#define rre(i,n) for(int i=(n);i>=0;i--)
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b);i>=(a);i--)
#define bw(a,b,c) (((a)<=(b))&&((b)<=(c)))
#define hello cout<<"hello"<<endl
#define spre(a) setprecision(a)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define IF(C,T,F) ((C)?(T):(F))
#define max3(a,b,c) max((a),max((b),(c)))
#define min3(a,b,c) min((a),min((b),(c)))
#define max4(a,b,c,d) max((a),max((b),max((c),(d))))
#define min4(a,b,c,d) min((a),min((b),min((c),(d))))
#define enl cout<<endl
#define declare(t,n) t n;cin>>n
#define EPS 1e-6
#define EPSIN(a,b) ((b)-EPS<=(a)&&(a)<=(b)+EPS)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef complex<int> point;

template<class InputIterator>
void dump(InputIterator first,InputIterator last,char delim=' '){
	for(InputIterator it=first;it!=last;it++){
		if(it!=first)cout<<delim;
		cout<<*it;
	}
}

ull p(ull x,ull y){
	if(y==0) return 1;
	ull A=p(x,y/2)%MOD;
	// return (y&1?((A*A)%MOD*x)%MOD: (A*A)%MOD);
	return (y&1?((A*A)*x):(A*A));
}

template<class T>
void swp(T &a,T &b){
	T t=a; a=b; b=t;
}

template<class T>
int h(T first,string t){
	T it=first;
	int c=0;
	for(int i=0;i<t.size();i++){
		if(*it!=t[i]) c++;
		it++;
	}
	return c;
}

ll gcd(ll a,ll b){
	if(b==0) return a;
	return gcd(b,a%b);
}

int main(void){
	string s,t;
	while(cin>>s,s!="."){
		cin>>t;
		if(s==t){cout<<"IDENTICAL"<<endl;continue;}
		std::vector<string> v1[2];
		std::vector<string> v2[2];
		bool b,flag=false;
		string temp;
		//*** v1 ***
		b=false;
		temp="";
		re(i,s.size()){
			if(s[i]=='\"'){
				b=!b;
				v1[b].push_back(temp);
				temp="";
			}
			else temp+=s[i];
		}
		if(s[s.size()-1]!='\"')v1[!b].push_back(temp);
		//*** v2 ***
		int aa=0;
		b=false;
		temp="";
		re(i,t.size()){
			if(t[i]=='\"'){
				b=!b;
				v2[b].push_back(temp);
				temp="";
			}
			else temp+=t[i];
		}
		if(t[t.size()-1]!='\"')v2[!b].push_back(temp);

		if(v1[0].size()!=v2[0].size())goto DEF;
		if(v1[1].size()!=v2[1].size())goto DEF;
		re(i,v1[1].size()){ // program
			if(v1[1][i]!=v2[1][i]) goto DEF;
		}
		re(i,v1[0].size()){ // strings
			if(v1[0][i]!=v2[0][i]) aa++;
			if(aa==2)goto DEF;
		}
		if(flag)goto IDE;
		else goto CLOSE;
		
DEF:
		cout<<"DIFFERENT"<<endl;
		continue;
IDE:
		cout<<"IDENTICAL"<<endl;
		continue;
CLOSE:
		cout<<"CLOSE"<<endl;
		continue;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define test(a) printf("(%3d)", a)
typedef long long ll;
typedef unsigned long long ull;
using namespace std;

const int MAXN = 5e4 + 10;

string a, b;
int i, j, cnt;
int flag1, flag2;
char str[205], tex[205];

int main (void) {
    while (~scanf("%s", str) && str[0] != '.') {
        scanf("%s", tex);
        i = j = cnt = 0;
        for (i = 0, j = 0; str[i] && tex[j]; i++, j++) {
            if (str[i] == '"') {
                flag1 = 1;
                while (str[++i] != '"') a.push_back(str[i]);
            }
            if (tex[j] == '"') {
                flag2 = 1;
                while (tex[++j] != '"') b.push_back(tex[j]);
            }
            if (flag1 && flag2) {
                cnt += (a != b);
            } else if (!flag1 && !flag2) {
                cnt += 2*(str[i] != tex[j]);
            } else {
                cnt += 2;
            }
            flag1 = flag2 = 0;
            a.clear(),b.clear();
            if (cnt >= 2) break;
        }
        if (str[i]) {
            cnt += 2;
        } else if (tex[j]) {
            cnt += 2;
        }
        if (cnt >= 2) printf("DIFFERENT\n");
        else if (cnt == 1) printf("CLOSE\n");
        else printf("IDENTICAL\n");
    }
    return 0;
}