Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

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

func cipher(text string, direction int, int_shift int) string {
	shift, offset := rune(int_shift), rune(26)
	runes := []rune(text)
	for index, char := range runes {
		switch direction {
		case 1:
			if char >= 'a' && char <= 'z'-shift || char >= 'A' && char <= 'Z'-shift {
				char = char + shift
			} else if char > 'z'-shift && char <= 'z' || char > 'Z'-shift && char <= 'Z' {
				char = char + shift - offset
			}
		case -1:
			if char >= 'a'+shift && char <= 'z' || char >= 'A'+shift && char <= 'Z' {
				char = char - shift
			} else if char >= 'a' && char < 'a'+shift || char >= 'A' && char < 'A'+shift {
				char = char - shift + offset
			}
		}
		runes[index] = char
	}
	return string(runes)
}

func main() {
	for {
		infos := strings.Split(nextString(), " ")
		plain := make([]string, len(infos))
		if len(infos) == 0 {
			break
		}
		// println(infos)
		Decryption:
			for i := 0; i < 26; i++ {
				for j := range infos {
					plain[j] = cipher(infos[j], 1, i)
				}
				for j := range plain {
					if plain[j] == "this" || plain[j] == "that" || plain[j] == "the" {
						break Decryption
					}
				}
			}
			fmt.Println(strings.Join(plain, " "))
	}
}

C++: #include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <cmath>
#include <complex>
#include <map>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define EPS 1e-8
#define F first
#define S second

static const double PI=6*asin(0.5);
typedef long long ll;
typedef complex<double> CP;
typedef pair<long long,int> P;
static const int INF=1<<24;

string s;

int main(){
	while(getline(cin,s)){
		rep(i,s.size()){
			if(s[i]>='a'&&s[i]<='z'){
				s[i]-='a';
			}
			else if(s[i]==13){
				s[i]=200;
			}
		}
		for(int i=0;;i++){
			bool f=false;
			//cout<<s.size()<<endl;
			rep(j,s.size()-3){
				if(s[j]=='t'-'a'&&s[j+1]=='h'-'a'&&((s[j+2]==0&&s[j+3]=='t'-'a')||(s[j+2]=='i'-'a'&&s[j+3]=='s'-'a')||s[j+2]=='e'-'a')){
					f=true;
					break;
				}
			}
			if(s[s.size()-3]=='t'-'a'&&s[s.size()-2]=='h'-'a'&&s[s.size()-1]=='e'-'a') f=true;
			if(f) break;
			else{
				rep(j,s.size()){
					if(s[j]<='z'-'a'&&s[j]>=0){
						s[j]=(s[j]+1)%('z'-'a'+1);
					}
				}
			}
		}
		rep(i,s.size()){
			if(s[i]<='z'-'a'&&s[i]>=0){
				s[i]+='a';
			}
			else if(s[i]==200){
				s[i]=13;
			}
		}
		cout<<s<<endl;
			
	}
	return 0;
}

C++: // includes
#include <cstdio>
#include <cstdint>
#include <iostream>
#include <iomanip>
#include <string>
#include <queue>
#include <stack>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <utility>
#include <functional>
#include <cmath>
#include <climits>
#include <bitset>

// macros
#define ll long long int
#define pb push_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a); i<(b);++i)
#define rep(i, n) FOR(i, 0, n)

using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;

// solve

int main(int argc, char const* argv[])
{
  string s;
  while(getline(cin, s)){
    FOR(i, 1, 26){
      string t = s;
      string res = "";
      rep(j, t.size()){
        if(!('a' <= s[j] && s[j] <= 'z')){
          res += t[j];
        }else{
          res += char(((int(t[j] - 'a') + i) % 26) + 'a');
        }
      }
      string tmp = "";
      bool flag = false;
      rep(j, res.size()){
        if(res[j] != ' ')tmp += res[j];
        else{
          if(tmp == "the" || tmp == "this" || tmp == "that"){
            flag = true;
            break;
          }
          tmp = "";
        }
      }
      if(flag){
        cout << res << endl;
        break;
      }
    }
  }
	return 0;
}

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 <fstream>
#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
using namespace std;

char shift(char c, int n) {
  if (c >= 'a' && c <= 'z')
    return (c + n <= 'z') ? c + n : 'a' + (c + n - 'z' - 1);
  else
    return c;
}

bool exist(string str, string c) {
  return str.find(c, 0) != string::npos;
}

int main() {
  // ifstream cin("../test.txt");
  vector<string> _the(26);
  vector<string> _this(26);
  vector<string> _that(26);
  _the[0] = "the";
  _this[0] = "this";
  _that[0] = "that";
  for (int i = 1; i < 26; i++) {
    for (int j = 0; j < 3; j++) {
      _the[i] += shift(_the[0][j], i);
    }
    for (int j = 0; j < 4; j++) {
      _this[i] += shift(_this[0][j], i);
      _that[i] += shift(_that[0][j], i);
    }
  }

  string str, nstr;
  // 復号化
  while (getline(cin, str)) {
    if (str.length() == 0) break;
    nstr = "";
    for (int i = 1; i < 26; i++) {
      if ( exist(str, _the[i]) || exist(str, _this[i]) || exist(str, _that[i])) {
        int len = str.length();
        for (int j = 0; j < len; j++) {
          nstr += shift(str.at(j), 26 - i);
        }
        break;
      }
    }

    cout << nstr << endl;
  }
  // 暗号化
  // while (getline(cin, str)) {
  //   for (int i = 1; i < 26; i++) {
  //     nstr = "";
  //     int len = str.length();
  //     for (int j = 0; j < len; j++) {
  //       nstr += shift(str[j], i);
  //     }
  //     cout << nstr << endl;
  //   }
  // }
}

C++: #include<bits/stdc++.h>
using namespace std;
void Caesarcipher(string &s,int c){
  if(c<0) c = 26+c%26;
  else c %= 26;
  for(int i=0;i<s.size();i++){
    if('a' <= s[i] && s[i] <= 'z'){
      s[i] += c;
      if(s[i] > 'z') s[i] -= 26;
      else if(s[i] < 'a') s[i] += 26;
    }
  }
}
int main(){
  string s;int i;
  while(getline(cin,s)){
    for(i=0;i<26;i++){
      Caesarcipher(s,1);
      if(s.find("the") != string::npos || s.find("this") != string::npos || s.find("that") != string::npos){
        cout << s << "\n";
      }
    }
  }
}