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;

int main()
{
  while(1){
    string row1,row2;
    string period(".");
    string cover("\"");
    string none("");

    cin>>row1;
    if(row1 == period){
      break;
    }
    cin>>row2;

    if(row1 == row2){
      cout<<"IDENTICAL"<<endl;
    }
    else{
      int size1 = row1.size();
      vector<string> Row1;
      string temp2;
      int j = 0;
      string temp1;

      for(int i = 0;i < size1;++i){ 
        temp1 = row1[i];
        if(temp1 == cover){
          if(j == 0 && i != 0){
            Row1.push_back(temp2);
            j = 1;
          }
          else if((j == 0 && i == 0) || j == 1){
            Row1.push_back(none);
            j = 2;
          }
          else{
            Row1.push_back(none);
            j = 0;
          }
        }
        else if(i == size1 - 1){
          if(j == 0){
            temp2 += temp1;
            Row1.push_back(temp2);
          }
          else{
            temp2 = temp1;
            Row1.push_back(temp2);
          }
        }
        else{
          if(j == 1){
            temp2 = temp1;
            j = 0;
          }
          else{
            temp2 += temp1;
          }
        }
      }

      int size2 = row2.size();
      vector<string> Row2;
      string temp3;
      j = 0;

      for(int i = 0;i < size2;++i){ 
        temp1 = row2[i];
        if(temp1 == cover){
          if(j == 0 && i != 0){
            Row2.push_back(temp3);
            j = 1;
          }
          else if((j == 0 && i == 0) || j == 1){
            Row2.push_back(none);
            j = 2;
          }
          else{
            Row2.push_back(none);
            j = 0;
          }
        }
        else if(i == size2 - 1){
          if(j == 0){
            temp3 += temp1;
            Row2.push_back(temp3);
          }
          else{
            temp3 = temp1;
            Row2.push_back(temp3);
          }
        }
        else{
          if(j == 1){
            temp3 = temp1;
            j = 0;
          }
          else{
            temp3 += temp1;
          }
        }
      }

      int Size1 = Row1.size();
      int Size2 = Row2.size();
      int count = 0;

      if(Size1 != Size2){
        cout<<"DIFFERENT"<<endl;
      }
      else{
        for(int i = 0;i <= Size1;++i){
          string check1,check2;
          check1 = Row1[i];
          check2 = Row2[i];

          if(i % 2 == 0){
            if(check1 != check2){
              cout<<"DIFFERENT"<<endl;
              break;
            }
          }
          else{
            if(check1 != check2){
              ++count;
            }
          }
          
          if(count == 2){
            cout<<"DIFFERENT"<<endl;
            break;
          }
        }
      }

      if(count == 1){
        cout<<"CLOSE"<<endl;
      }
    }
  }
  
  return 0;
}

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

int main(){
  while(true){
    string s1;
    cin >> s1;
    if(s1==".")break;

    string s2;
    cin >> s2;
    if(s1==s2){
      cout << "IDENTICAL" << endl;
      continue;
    }

    string t1=s1;
    string t2=s2;

    while(true){
      size_t d1b = t1.find('\"');
      if(d1b==string::npos)break;
      t1.replace(d1b,1,"@");

      size_t d1e = t1.find('\"');
      t1.replace(d1e,1,"@");

      size_t d2b = t2.find('\"');
      if(d2b==string::npos)break;
      t2.replace(d2b,1,"@");

      size_t d2e = t2.find('\"');
      t2.replace(d2e,1,"@");

      string u1 = s1;
      u1.replace(d1b+1,d1e-d1b-1,"");
      string u2 = s2;
      u2.replace(d2b+1,d2e-d2b-1,"");

      if(u1==u2){
        t1=u1;
        t2=u2;
        break;
      }
    }

    if(t1==t2){
      cout << "CLOSE" << endl;
    }else{
      cout << "DIFFERENT" << endl;
    }
  }

  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define REP(i, n) rep(i, 0, n)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
using namespace std;
typedef pair<int, int> P;
const int mod = 1000000007;
const int INF = 1e12;

vector<string> split(const string &s,char c=' '){
    vector<string> ret;
    stringstream ss(s);
    string t;
    while(getline(ss,t,c)){
        ret.push_back(t);
    }
    return ret;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    while(1){
        string s, t;
        cin >> s;
        if(s == ".") break;
        cin >> t;
        if(s == t){
            cout << "IDENTICAL" << endl;
            continue;
        }
        char c = '"';
        vector<string> ss = split(s, c);
        vector<string> tt = split(t, c);
        int cnt = 0;
        if(ss.size() != tt.size()) cnt = INF;
        rep(i, 0, min(ss.size(), tt.size())){
            if(i % 2 == 0){
                if(ss[i] != tt[i]) cnt = INF;
            }else{
                if(ss[i] != tt[i]) cnt++;
            }
        }
        if(cnt <= 1){
            cout << "CLOSE" << endl;
        }else{
            cout << "DIFFERENT" << endl;
        }
    }
}