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 <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <unordered_map>
#include <list>
#include <numeric>
#include <utility>
#include <iterator>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <ctime>
#include <cassert>

#define INF 1000000000
#define LINF 9000000000000000000
#define mod 1000000007

#define rep(i,n) for(int i=0;i<int(n);i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define REP(i,a,b) for(int i=(a);i<int(b);i++)
#define all(x) (x).begin(),x.end()
#define pb push_back
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<long long>vll;
typedef pair<int,int> pi;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int ddx[8]={-1,-1,0,1,1,1,0,-1};
int ddy[8]={0,1,1,1,0,-1,-1,-1};
bool debug=false;

/*---------------------------------------------------*/

string solve(string s,string ss){
  if(s==ss)return "IDENTICAL";
  
  vector<string> vs;
  string add="";
  for(int i=0;i<s.size();i++){
    if(s[i]=='"'){
      vs.pb(add);
      add="";
    }else{
      add+=s[i];
    }
  }
  vs.pb(add);

  add="";
  vector<string> vss;
  for(int i=0;i<ss.size();i++){
    if(ss[i]=='"'){
      vss.pb(add);
      add="";
    }else{
      add+=ss[i];
    }
  }
  vss.pb(add);

  int cnt=0;
  // for(int i=0;i<vs.size();i++)cout<<"debug: "<<vs[i]<<" "<<vss[i]<<" ==> "<<(vs[i]==vss[i])<<endl;
  if(vs.size()!=vss.size())return "DIFFERENT";
  for(int i=0;i<min(vs.size(),vss.size());i++){
    // cout<<"debug: "<<vs[i]<<" "<<vss[i]<<endl;
    if(i%2==0){
      if(vs[i]!=vss[i])return "DIFFERENT";
    }else{
      if(vs[i]!=vss[i])cnt++;
    }
  }
  
  // cout<<cnt<<endl;
  if(cnt<=1)return "CLOSE";
  else return "DIFFERENT";
}

int main(){
  string s,ss;
  while(cin>>s){
    if(s==".")break;
    cin>>ss;
    cout<<solve(s,ss)<<endl;;
  }
  return 0;
}

C++: #include<iostream>
#include<sstream>
using namespace std;

int main(){
	while(1){
		string s1,s2;
		cin >> s1;
		if(s1 == ".") return 0;
		cin >> s2;
		string s11[200], s22[200];
		for(int i=0;i<200;i++){
			s11[i] = "."; s22[i] = ".";
		}
		int now1=0,now2=0;
		for(int i=0;i<(int)s1.length();i++){
			if(s1[i] == '"'){
				now1++;
				s11[now1] = "";
			}else s11[now1] += s1[i];
		}
		for(int i=0;i<(int)s2.length();i++){
			if(s2[i] == '"'){
				now2++;
				s22[now2] = "";
			}else s22[now2] += s2[i];
		}
		int d=0;
		for(int i=0;i<200;i++){
			if(s11[i] != s22[i]){
				if(i&1){
					d++;
				}else d+=2;
			}
		}
		if(d==0)cout<<"IDENTICAL";
		else if(d==1)cout<<"CLOSE";
		else cout<<"DIFFERENT";
		cout<<"\n";
	}
}

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

int main() {

    while(1){

        string s1,s2;

        cin >> s1;

        if(s1[0] == '.' && s1.size() == 1){
            break;
        }

        cin >> s2;

        string::iterator itr1 = s1.begin(),itr2 = s2.begin();

        bool firstdiff = false;

        bool is_into_quotation = false;

        string ans = "INCOLLECT";

        while(1){

            if(*itr1 == '"' && *itr2 == '"'){
                if(is_into_quotation){
                    is_into_quotation = false;
                }
                else{
                    is_into_quotation = true;
                }
            }

            if(*itr1 != *itr2){
                if(is_into_quotation && !firstdiff){

                    while(*itr1 != '"'){
                        itr1++;
                    }

                    while(*itr2 != '"'){
                        itr2++;
                    }

                    is_into_quotation = false;


                    firstdiff = true;
                }
                else{
                    ans = "DIFFERENT";
                    break;
                }
            }

            itr1++; itr2++;

            if(itr1 == s1.end() && itr2 == s2.end()){
                if(firstdiff){
                    ans = "CLOSE";
                }
                else{
                    ans = "IDENTICAL";
                }
                break;
            }

        }

        cout << ans << endl;

    }

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