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<cmath>
#include<algorithm>
#include<cctype>
#include<queue>
#include<deque>
#include<regex>
#include<stack>
#include<stdio.h>
#include<vector>
#include<set>
#include<map>
#include<iomanip>

#define rep(i, n) for(int i=0;i<n;i++)

typedef int long long ll;
using namespace std;
typedef pair<int, int> P;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
const ll MOD = 1e9 + 7;
static const int MAX = 100;
static const int INF = (1 << 23);

string change(string s){
    string ret;
    int i=0;
    while(i<s.size()) {
        if (s[i] == '\"'){
            i++;
            while(i<s.size()&&s[i]!='\"'){
                i++;
            }
            ret+='\"';
            i++;
    }else{
            ret+=s[i];
            i++;
        }
    }
    return ret;
}
vector<string> nuke(string s){
    vector<string> res;
    int i=0;
    while(i<s.size()) {
        if (s[i] == '\"'){
            string ret;
            i++;
            while(i<s.size()&&s[i]!='\"'){
                ret+=s[i];
                i++;
            }
            res.push_back(ret);
            i++;
        }else{
            i++;
        }
    }
    return res;
}
int main() {
    string s1,s2;
    while(true){
        cin>>s1;
        if(s1[0]=='.'&&s1.size()==1)break;
        cin>>s2;

        vector<string> d1;
        vector<string> d2;
        string ss1=change(s1);
        string ss2=change(s2);
        d1=nuke(s1);
        d2=nuke(s2);
        if(s1==s2){
            cout<<"IDENTICAL"<<endl;
        }else if(ss1!=ss2) {
            cout<<"DIFFERENT"<<endl;
        }else{
                vector<string> d3;
                vector<string> d4;
                if(d1.size()>d2.size()){
                    d3=d1;
                    d4=d2;
                }else{
                    d3=d2;
                    d4=d1;
                }
                if(d3.size()-d2.size()>=2){
                    cout<<"DIFFERENT"<<endl;
                }else {
                    int c=0;
                if(d3.size()==d4.size()){
                    rep(i,d3.size()){
                        if(d3[i]!=d4[i])c++;
                    }
                    if(c==1){
                        cout<<"CLOSE"<<endl;
                    }else{
                        cout<<"DIFFERENT"<<endl;
                    }
                }else{
                    for(int i=0;i<d3.size();i++){
                        int d=0;
                        while(d<d4.size()){
                            if(i!=d){
                                if(d3[i]!=d4[d])c++;
                                d++;
                            }else{
                            }
                        }
                        if(c==0){
                            cout<<"CLOSE"<<endl;
                        }else{
                            cout<<"DIFFERENT"<<endl;
                        }
                    }



                }

            }
        }

    }


    return 0;
}

C++: #include <stdio.h>
#include <string.h>

int main(void) {
	while(1) {
		//入力
		char str1[201], str2[201];// 問題文ではs1,s2となっています。
		scanf("%s", str1);
		if(str1[0] == '.' && str1[1] == '\0') break;
		scanf("%s", str2);

		//処理
		if(strcmp(str1, str2) == 0){
			printf("IDENTICAL\n"); //2つの文字列は完全に一致したなら、IDENTICALを出力。
			continue;
		}

		bool inQuotes = false; //二重引用府(")の中ならtrue,外ならfalse
		int i=0, j=0;
		int diffCount=0;//文字列定数(奇数番目の二重引用符とその次の二重引用符の間の文字の並び)がstr1とstr2とで異なってる数。
		while(str1[i] != '\0' || str2[j] != '\0') {
			if(str1[i] != str2[j]) {
				if(inQuotes == false) {
					diffCount = 2;//二重引用符の外で異なっている場合は、その時点でDIFFERENT。
					break;
				} else{
					diffCount++;
					if(diffCount == 2) break;
					//str1,str2共に、二重引用符(")のところまで、進める。
					while(str1[i] != '"') i++;
					while(str2[j] != '"') j++;
					inQuotes = false;
				}
			} else if(str1[i] == '"' && str2[j] == '"') {
				inQuotes = !inQuotes;//trueならfalseに、falseならtureにする。
			}
			i++; j++;
		}

		//出力
		if(diffCount == 1){
			printf("CLOSE\n");
		} else{
			printf("DIFFERENT\n");
		}
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>

using namespace std;

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 = "";
		}
		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 == 0) {
				if (v1[i] != v2[i]) {
					cout << "DIFFERENT" << endl;
					continue;
				}
			}
			else {
				if (v1[i] != v2[i]) {
					cnt++;
				}
			}
		}
		if (cnt > 1) {
			cout << "DIFFERENT" << endl;
		}
		else {
			cout << "CLOSE" << endl;
		}
	}
	
	return 0;
}