Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func incrementByte(b byte) byte {
	if b >= 97 && b < 122 {
		return b + 1
	} else if b == 122 {
		return 97
	}
	return b
}

func main() {
	scanner.Split(bufio.ScanLines)

	for {
		line := nextString()
		if len(line) == 0 {
			break
		}
		for i := 0; i <= 26; i++ {
			decoded := []byte{}
			for j := 0; j < len(line); j++ {
				decoded = append(decoded, incrementByte(line[j]))
			}
			line = string(decoded)
			if strings.Contains(line, "the") || strings.Contains(line, "this") || strings.Contains(line, "that") {
				fmt.Println(line)
				break
			}
		}
	}
}

C++: #include <iostream>
#include <string>
using namespace std;
int main() {string here,ans;while (getline(cin,here)) for (int i=0;i<26;i++) {ans=here;for (int j=0;j<ans.size();j++) if (ans[j]>='a' && ans[j]<='z') ans[j]=(ans[j]-'a'+i)%26+'a';if (ans.find("that",0) != string::npos || ans.find("this",0) != string::npos || ans.find("the",0) != string::npos) {cout<<ans<<endl;break;}} return 0;}

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

using namespace std;

int main() {
    string a;
    
    getline(cin,a);
    
    while (1){
        if(a.find("this")!=-1 || a.find("the")!=-1 || a.find("that")!=-1){
            break;
        }
        
        for(int i=0; i<a.length(); i++){
            if(a[i]==' '|| a[i]=='.'){
                
            }else if(a[i]=='z'){
                a[i]='a';
            }else{
                a[i]++;
            }
        }

    }
    cout<<a<<endl;;
    
    
    return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<sstream>
int main()
{
	std::vector<std::string>result;
	for (std::string s; std::getline(std::cin, s);)
	{
		int delta = 0;
		std::stringstream ss;
		ss << s;
		while (!ss.eof())
		{
			std::string temp;
			ss >> temp;
			if (temp.length() == 3 && temp[0] != '.' && temp[1] != '.' && temp[2] != '.')
			{
				int d1 = temp[0] - 't';
				int d2 = temp[1] - 'h';
				int d3 = temp[2] - 'e';
				for (auto i : { &d1,&d2,&d3 })
				{
					if (*i < 0)
					{
						*i += 26;
					}
				}
				if (d1 == d2 && d2 == d3)
				{
					delta = d1;
					break;
				}
			}
			else if (temp.length() == 4 && temp[0] != '.' && temp[1] != '.' && temp[2] != '.' && temp[3] != '.')
			{
				int d1 = temp[0] - 't';
				int d2 = temp[1] - 'h';
				int d3 = temp[2] - 'i';
				int d4 = temp[3] - 's';
				for (auto i : { &d1,&d2,&d3,&d4 })
				{
					if (*i < 0)
					{
						*i += 26;
					}
				}
				if (d1 == d2 && d2 == d3 && d3 == d4)
				{
					delta = d1;
					break;
				}
				d1 = temp[0] - 't';
				d2 = temp[1] - 'h';
				d3 = temp[2] - 'a';
				d4 = temp[3] - 't';
				for (auto i : { &d1,&d2,&d3,&d4 })
				{
					if (*i < 0)
					{
						*i += 26;
					}
				}
				if (d1 == d2 && d2 == d3 && d3 == d4)
				{
					delta = d1;
					break;
				}
			}
		}
		if (delta > 0)
		{
			delta -= 26;
		}
		result.push_back(std::string(s.length(), 'a'));
		for (int i = 0; i < s.length(); i++)
		{
			result.back()[i] = 'a' <= s[i] && s[i] <= 'z' ? (s[i] - 'a' - delta) % 26 + 'a' : s[i];
		}
	}
	for (auto i : result)
	{
		std::cout << i << std::endl;
	}
	return 0;
}

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

int main(void){
  while(true){
    string str;
    if(!getline(cin, str)) break;;
    while(true){
      for(int i = 0; i < str.size(); i++){
        if(isalpha(str[i]) && str[i] == 'z'){
          str[i] = 'a';
        }else if(isalpha(str[i])){
          str[i]++;
        }
      }
      if(str.find("that") != string::npos || str.find("this") != string::npos || str.find("the") != string::npos) break;
    }
    cout << str << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<string>
#define num 26
using namespace std;

int main(){
	int i;
	string str;
	getline(cin, str);
	string strcp = str;
	string::iterator si;
	for(i=0;i<num;i++){
		if(  strcp.find("this") != string::npos
		  || strcp.find("that") != string::npos
		  || strcp.find("the" ) != string::npos){
			cout << strcp << endl;
		}
		si = strcp.begin();
		while(si != strcp.end()){
			if('a' <= *si && *si <= 'y'){
				*si = *si + char(1);
			}else if(*si == 'z'){
				*si = 'a';
			}
			si++;
		}
	}
	return 0;
}

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

typedef pair<string, string> P;

P next_word(string sentence) {
  if (sentence.empty()) return make_pair(string(""), string(""));
  if (sentence[0] == ' ' || sentence[0] == '.') {
    return make_pair("", sentence.substr(1));
  } else {
    P recur = next_word(sentence.substr(1));
    return make_pair(sentence[0] + recur.first, recur.second);
  }
}

bool acceptable(string sentence) {
  P p = next_word(sentence);

  while (! p.first.empty() ) {
    if (p.first == "this" || p.first == "the" || p.first == "that")
      return true;

    p = next_word(p.second);
  }
  return false;
}

char slip(char c) {
  if (c < 'a' || 'z' < c) return c;
  
  string alphabet = "abcdefghijklmnopqrstuvwxyza";
  int index = (int)(c - 'a');
  return alphabet[index + 1];
}

char slip(char c, int n) {
  for (int i = 0; i < n; i++)
    c = slip(c);

  return c;
}

string slip(string code, int n) {
  string val;
  for (int i = 0, len = code.length(); i < len; i++)
    val += slip(code[i], n);

  return val;
}

string decode(string code) {
  for (int i = 1; i < 27; i++) {
    string sentence = slip(code, i);
    if (acceptable(sentence))
      return sentence;
  }

  return "";
}

int main() {
  string code;
  while ( getline(cin, code) )
    cout << decode(code) << endl;
}

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

int main(void)
{
	int i;
	int len;
	int f;
	char str[128];
	
	while (fgets(str, 100, stdin) != NULL){
		f = 0;
		while (1){
			len = strlen(str);
			for (i = 0; i < len; i++){
				if (strncmp(&str[i], "the", 3) == 0){
					f = 1;
				}
				if (strncmp(&str[i], "this", 4) == 0){
					f = 1;
				}
				if (strncmp(&str[i], "that", 4) == 0){
					f = 1;
				}
			}
			if (f == 1){
				break;
			}
			for (i = 0; i < len; i++){
				if (str[i] >= 'a' && str[i] < 'z'){
					str[i]++;
				}
				if (str[i] == 'z'){
					str[i] = 'a';
				}
			}
		}
		printf("%s", str);
	}
	return (0);
}

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

// determine whether it is "the","this" or "that"
char is_article(string w) {
	// if (w == "the" || w == "this" || w == "that") {
	// 	return '\0';
	// }
	char sh = 't' - w.front();
	for_each(w.begin(),w.end(),[sh](char &c) {
		c += sh;
		if (c > 'z') {
			c -= (char)26;
		} else if (c < 'a') {
			c += (char)26;
		}
	});
	if (w != "the" && w != "this" && w != "that") {
		sh = '\0';
	}
	return sh;
}

int main() {
	string s;
	while (getline(cin,s)) {
		istringstream stream(s);
		string w;
		char sh;
		while (stream >> w) {
			if ((sh = is_article(w)) != '\0') {
				break;
			}
		}
		for_each(s.begin(),s.end(),[sh](char &c) {
			if (c >= 'a' && c <= 'z') {
				c += sh;
				if (c > 'z') {
					c -= (char)26;
				} else if (c < 'a') {
					c += (char)26;
				}
			}
		});
		cout << s << endl;
	}
}

C++: while line = STDIN.gets

	len = line.length

	while !(line =~ /(the|this|that)/)
	
		for i in 0..len-1 do
			if( line[i,1] =~ /[a-z]/)
				if(line[i,1] =~ /z/)
					line[i] = "a"
				else
					line[i] = line[i].succ
				end
			end
		end
	end
	
	puts line
	
end