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

// determine whether it is "the","this" or "that"
char is_article(string w) {
	char sh = '\0'; // shift defaults to 0
	if (w.size() == 3) {
		sh = 't' - w.front();
		for_each(w.begin(),w.end(),[sh](char &c) {
			c += sh;
			c -= c > 'z' ? 'z'-'a'+1 : '\0';
		});
		if (w != "the") {
			sh = '\0';
		}
	} else if (w.size() == 4) {
		sh = 't' - w.front();
		for_each(w.begin(),w.end(),[sh](char &c) {
			c += sh;
			c -= c > 'z' ? 'z'-'a'+1 : '\0';
		});
		if (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;
				c -= c > 'z' ? 'z'-'a'+1 : '\0';
			}
		});
		cout << s << endl;
	}
}

C++: #include <bits/stdc++.h>
 
using namespace std;
 
#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define repr(i, j) for(int i = j; i >= 0; --i)
#define INF (1 << 30)
#define MOD 1e9 + 7
 
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
 
int main() {
    string s;
    while(getline(cin, s)){
    	rep(i, 26) {
	    	rep(j, s.size()) {
	            if('a' <= s[j] && s[j] < 'z') s[j] = s[j] + 'a';
	            else if(s[j] == 'z') s[j] = 'a';
	        }
	        if(s.find("the") != string::npos || s.find("this") != string::npos || s.find("that") != string::npos){
                cout << s << endl;
            }
	    }
    }
    return 0;
}

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

bool dec(string str, string array[]) {
  for (int i = 0; i < 3; i++) {
    if (str.find(array[i], 0) != string::npos) return false;
  }
  return true;
}

int main() {
  string array[3] = {"the", "this", "that"};
  while (1) {
    string str;
    getline(cin, str);
    while (dec(str, array)) {
      for (int i = 0; str[i] != '\0'; i++) {
	if ('a' <= str[i] && str[i] <= 'z') {
	  if (str[i] == 'z') str[i] = 'a';
	  else str[i]++;
	}
      }      
    }
    cout << str << endl;
  }
  return 0;
}

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

int main(){
   string str;
   bool ans=false;
   getline(cin,str);
   
   string::iterator ite=str.begin();
   
   while(1){
      //cout << str.find("the");
      if(str.find("the")<str.size()) ans=true;
      else if(str.find("this")<str.size()) ans=true;
      else if(str.find("that")<str.size()) ans=true;
      if(ans) break;
      for(int i=0;i<str.size();i++){
         if(*(ite+i)!=' '&&*(ite+i)!='.') *(ite+i)-=1;
      }
   }
   cout << str << endl;
}

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

bool checkString(int* key, string s);
void rotateChar(string* s, int i);

int main()
{
    list<string> table;
    char text[80];
	int size=0;

	for(size=0; cin.get(text[size]); size++ ){;}

	char ch;
	string s;
	for(int i=0; (ch=text[i])!=EOF; i++){
		if(ch!=' ')s.push_back(ch);
		else{ table.push_back(s), s.clear();}
	}		

    int key; // ずらす文字数
    list<string>::iterator i;
    for(i=table.begin(); i!=table.end(); i++){
        // cout << *i << " ";
        if( i->size() == 3 || i->size() == 4 )
            if( checkString(&key, *i) ) break;
    }
	
	for(int i=0; i<size; i++){
		char ch = text[i];
		if(isalpha(ch)){
        char c = ch - 'a';
        ch = 'a' + (c+key)%26;
		}
		cout.put(ch);
	}

    return 0;
}

void rotateChar(string* s, int i) // iは何文字ずらしたいか
{

    for(int j=0; j<s->size(); j++){
        if(!isalpha(s->at(j))){continue;}
        char c = s->at(j) - 'a';
        s->at(j) = 'a' + (c+i)%26;
    }
}

bool checkString(int* key, string s)
{

    for(int i=0; i<26; i++){
        string tmp = s;
        rotateChar(&tmp, i);
        // cout << tmp << endl;
        if( tmp=="the" || tmp=="this" || tmp=="that" ){
            *key=i;
            return true;
        }
    }
    return false;
}

C++: #include <iostream>
#include <cmath>
#include <cstdio>
#include <vector>

using namespace std;
string s;
char decrypt[100];
int key,i;

int main(){
    while(getline(cin,s)){
        const char *encrypt = s.c_str();
        while(encrypt[i] != '\0'){
            if(encrypt[i] - encrypt[i+1] == 12){
                key = 't' - encrypt[i];
                break;
            }
            i++;
        }

        i = 0;
        while(encrypt[i] != '\0'){
            if(encrypt[i] <= 'z' && encrypt[i] >= 'a'){
                decrypt[i] = (encrypt[i] - 'a' + key + 26) % 26 + 'a';
            }
            else{
                decrypt[i] = encrypt[i];
            }
            i++;
        }
        while(i <= 50){
            decrypt[i] = '\0';
            i++;
        }
        printf("%s\n", decrypt);
    }
    return 0;
}