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;

vector<pair<string, bool> > Parse_String(string &S) {
    vector<pair<string, bool> > res;
    bool flg = false;
    for(int i = 0; i < S.size(); ) {
        int j = i;                  // [i, j)
        while(j < S.size() && S[j] != '"') ++j;
        res.push_back(pair<string, bool>(S.substr(i,j-i), flg));
        flg = !flg;
        i = j + 1;
    }
    return res;
}

bool solve() {
    string S1;
    cin >> S1;
    if(S1 == ".") return false;
    string S2;
    cin >> S2;

    vector<pair<string, bool> > List1, List2;
    List1 = Parse_String(S1);
    List2 = Parse_String(S2);
    /*
    cout << "S1: "<< endl;
    for(int i = 0; i < List1.size(); ++i) {
        cout << List1[i].first << " " << List1[i].second << endl;;
    }

    cout<< "S2: " << endl;
    for(int i = 0; i < List2.size(); ++i) {
        cout << List2[i].first << " " << List2[i].second << endl;;
    }
    */

    if(List1.size() != List2.size()) {
        cout << "DIFFERENT" << endl;
        return true;
    }

    int N = List1.size();
    int res = 0;
    for(int i = 0; i < N; ++i) {
        auto &p1 = List1[i];
        auto &p2 = List2[i];
        if(p1.second) 
        {
            if(p1.first != p2.first) ++res;
        }
        else 
        {
            if(p1.first != p2.first) {
                cout << "DIFFERENT" << endl;
                return true;
            }
        }
    }
    if(res <= 0) { cout << "IDENTICAL" << endl; }
    else if(res == 1) { cout << "CLOSE" << endl; }
    else { cout << "DIFFERENT" << endl; }
    return true;
}

int main() {
    while(solve());
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
using namespace std;
string s1, s2;

int main() {

  while (1) {
    int count = 0;
    int n1 = 0;
    int n2 = 0;
    int error = 0;

    cin >> s1 >> s2;
    if(s1 == ".")
      break;

    if(s1 == s2) {
      cout << "IDENTICAL" << endl;
      break;
    }
    else if(s1[n1] != s2[n2]) {
      cout << "DIFFERENT" << endl;
      break;
    }

    while(1) {
      if(s1[n1] == '"' && s2[n2] == '"') {
        while(1) {
          if (s1[n1] != s2[n2]) count++;
          if(s1[n1] != '"') n1++;
          if(s2[n2] != '"') n2++;
          if (s1[n1] == '"' && s2[n2] == '"') {
            if(count > 0) error++;
            break;
          }
        }
      }
      if(n1 != s1.size()) n1++;
      if(n2 != s2.size()) n2++;
      if(n1 == s1.size() && n2 == s2.size())  {
        if (error >= 2 ) {
          cout << "DIFFERENT" << endl;
          break;
        }
        else {
          cout << "CLOSE" << endl;
          break;
        }
      }
    }
  }

  return 0;
}