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>
using namespace std;
int main(void){
    string s;
    while (cin>>s) {
        if (s==".") {
            break;
        }
        int flag=0;
        string tmp="";
        string other="";
        std::deque<string> S;
        std::deque<string> other_S;
        for (int i=0;i<s.size();i++) {
            if (flag==0) {
                if (s[i]=='"') {
                    flag=1;
                    other_S.emplace_back(other);
                    other="";
                } else {
                    other+=s[i];
                    if (i==s.size()-1) {
                        other_S.emplace_back(other);
                    }
                }
            } else {
                if (s[i]=='"') {
                    flag=0;
                    S.emplace_back(tmp);
                    tmp="";
                } else {
                    tmp+=s[i];
                }
            }
        }
        string t;
        cin>>t;
        tmp="";
        other="";
        flag=0;
        std::deque<string> T;
        std::deque<string> other_T;
        for (int i=0;i<t.size();i++) {
            if (flag==0) {
                if (t[i]=='"') {
                    flag=1;
                    other_T.emplace_back(other);
                    other="";
                } else {
                    other+=t[i];
                    if (i==t.size()-1) {
                        other_T.emplace_back(other);
                    }
                }
            } else {
                if (t[i]=='"') {
                    flag=0;
                    T.emplace_back(tmp);
                    tmp="";
                } else {
                    tmp+=t[i];
                }
            }
        }
        /*
        for (auto x:S) {
            cout<<x<<endl;
        }
        cout<<endl;
        for (auto xx:T) {
            cout<<xx<<endl;
        }
        cout<<endl;
        for (auto xxx:other_S) {
            cout<<xxx<<endl;
        }
        cout<<endl;
        for (auto xxxx:other_T) {
            cout<<xxxx<<endl;
        }
        cout<<endl;*/
        if (S.size()!=T.size()||other_S.size()!=other_T.size()) {
            cout<<"DIFFERENT"<<endl;
        } else {
            flag=0; //identical
            if (S.size()!=0&&T.size()!=0) {
                for (int i=0;i<S.size();i++) {
                    if (flag==0) {
                        if (S[i]!=T[i]) {
                            flag=1; //close
                        }
                    } else {
                        if (S[i]!=T[i]) {
                            flag=2; //different
                        }
                    }
                }
            }
            if (other_S.size()!=0&&other_T.size()!=0) {
                for (int i=0;i<other_S.size();i++) {
                    if (other_S[i]!=other_T[i]) {
                        flag=2;
                    }
                }
                if (flag==0) {
                    cout<<"IDENTICAL"<<endl;
                } else if (flag==1) {
                    cout<<"CLOSE"<<endl;
                } else {
                    cout<<"DIFFERENT"<<endl;
                }
            } else {
                if (flag==0) {
                    cout<<"IDENTICAL"<<endl;
                } else if (flag==1) {
                    cout<<"CLOSE"<<endl;
                } else {
                    cout<<"DIFFERENT"<<endl;
                }
            }
        }
    }
}

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

bool chk(std::string tmp1,std::string tmp2,bool *odd,int *cnt);

int main(){
    int cnt;
    bool odd;
    bool flag = false;
    std::string str1;
    std::string str2;
    std::string tmp1;
    std::string tmp2;
    while(true){
        odd = false;
        cnt = 0;
        while(std::getline(std::cin,str1)){
            if(str1 == "."){
                flag = true;
                break;
            }
            std::istringstream iss1(str1);
            std::getline(std::cin,str2);
            std::istringstream iss2(str2);
            while(iss1 >> tmp1){
                iss2 >> tmp2;
                if(chk(tmp1,tmp2,&odd,&cnt)){
                    break;
                }
            }
            
            if(cnt==0){
                std::cout << "IDENTICAL\n";
            }else if(cnt==1){
                std::cout << "CLOSE\n";
            }else{
                std::cout << "DIFFERENT\n";
            }
        }
        if(flag){
            break;
        }
    }
}

bool chk(std::string tmp1,std::string tmp2,bool *odd,int *cnt){
    if(tmp1!=tmp2){
        if(*odd){
            (*cnt)++;
        }else{
            (*cnt) += 2;
            return true;
        }

        if(*odd){
            (*odd) = false;
        }else{
            (*odd) = true;
        }
    }
    return false;
}