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<stdio.h>
 #include<string>
 #include<math.h>
 #include<iomanip>
 #include<algorithm>
 #include<string.h>
 #include<cctype>
 #include<map>
 #include<set>
 #include<vector>
 #include<sstream>
 #include<stack>
 
 using namespace std;
  
 int main()
 {
   string a,b;
   while(cin>>a)
   {
     for(int i=0;i<a.length();i++)
     {
       if(a[i]>='a'&&a[i]<='z')
       { 
         char temp= a[i]<'e' ? (a[i]+26-4): (a[i]-4);
         b+=temp;
       }         
       else b+=a[i]; 
     }             
     cout<<b<<endl;
   }
   //while(1);      
   return 0;    
 }

C++: #include <iostream>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
using namespace std;

int main()
{
    for(;;){
        string s;
        getline(cin, s);
        if(s == "")
            return 0;
    
        int n = s.size();
        for(;;){
            bool bl=false;
            for(int i=0; i<n; ++i){
               if('a' <= s[i] && s[i] <= 'z'){
                   if(s[i] == 'z')
                           s[i] = 'a';
                   else
                           ++ s[i];
               }
           }
           istringstream iss(s);
           string s1;
           while(iss >> s1){
               if(s1 == "the" || s1 == "this" || s1 == "that"){
                       cout << s << endl;
                       bl=true;
                       break;
               }
            }
           if(bl) break;
         }      
    }
}

C++: #include <iostream>
#include <string>
using namespace std;
int main()
{
	string str,t;
	while(getline(cin,str))
	{
		for(int i = 0;i < 26;++i)
		{
			t = str;
			for(int j = 0;j < str.size();++j)
			{
				if(t[j] == ' ' || t[j] == '.') continue;
				t[j] = (t[j] - 'a' + i) % 26 + 'a';
			}
			if(t.find("that",0) != string::npos || t.find("this",0) != string::npos || t.find("the",0) != string::npos){
				cout << t << endl;
				break;
			}
		}
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
using namespace std;
char CaesarChar(char );
string CaesarString(string s);
vector<string> CaesarVector(vector<string> v);
vector<string> SolveCaesar(vector<string> v);
int main() {
  string s;
  while( getline(cin,s)) {  
    vector<string> array;
    int space=0;
    int next_space=0;    
    for(int i=0;i<(int)s.size();i++) {
      if(s[i]== ' '){
	next_space=i;
	string tmp="";
	for(int j=space;j<next_space;j++)
	  tmp+=s[j];
	space=next_space+1;
	array.push_back(tmp);
      }
    }
    string tmp="";
    for(int i=next_space+1;i<(int)s.size();i++) 
      tmp+=s[i];
    array.push_back(tmp);
    vector<string> answer=SolveCaesar(array);
    for(int i=0;i<(int)answer.size();i++)
      cout<<answer[i]<<" "; 
    cout<<endl;
  }
  return 0;
}
char CaesarChar(char c) {
  if(c=='z')
    return 'a';
  return char(c+1);
}
string CaesarString(string s) {
  string tmp="";
  for(int i=0;i<(int)s.size();i++)
    tmp+=CaesarChar(s[i]);
  return tmp;
}
vector<string> CaesarVector(vector<string> v) {
  vector<string> tmp;
  for(int i=0;i<(int)v.size();i++) 
    tmp.push_back(CaesarString(v[i]));
  return tmp;
}
vector<string> SolveCaesar(vector<string> v) {
  for(int i=0;i<(int)v.size();i++) {
    if(v[i]=="the" || v[i]=="this" || v[i]=="that")
      return v;
  } 
  return SolveCaesar(CaesarVector(v));
}

C++: #include<iostream>
#include<string>
int main(){
	std::string str;
	while(std::getline(std::cin,str)){
	for(int i=0;i<str.size();i++){
		if(str[i]!=' '&&str[i]!='z'&&str[i]=='.')str[i]+=1;
		if(str[i]=='z')str[i]-=25;
	}
	std::cout<<str<<std::endl;
	}
	return 0;
}

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

int main(){

	char s[1000];
	while (gets(s)){
		
		int diff;
		int flag = false;
		//一番最初に｛the,that,this｝がある場合
		diff = s[0] - 't';
		if ((s[1] - diff) == 'h'){
			//printf("%c\n", s[j+1] - diff);
			if ((s[2] - diff) == 'e'){
				//printf("%c\n", s[j + 2] - diff);
				if (s[3] == ' '){
					flag = true;
				}
			}
			else if ((s[2] - diff) == 'a'){
				//printf("%c\n", s[j + 2] - diff);
				if ((s[3] - diff) == 't'){
					//printf("%c\n", s[j + 3] - diff);
					if (s[4] == ' '){
						flag = true;
					}
				}
			}
			else if ((s[2] - diff) == 'i'){
				//printf("%c\n", s[j + 2] - diff);
				if ((s[3] - diff) == 's'){
					//printf("%c\n", s[j + 3] - diff);
					if (s[4] == ' '){
						flag = true;
					}
				}
			}
		}

		if (!flag){
			//一番以降に｛the,that,this｝がある場合
			for (int j = 1; j < strlen(s); j++){
				if ((s[j]) == ' '){
					diff = s[j + 1] - 't';
					if ((s[j + 1] - diff) == 't'){
						//printf("diff:%d\n", diff);
						if ((s[j + 2] - diff) == 'h'){
							//printf("%c\n", s[j+1] - diff);
							if ((s[j + 3] - diff) == 'e'){
								//printf("%c\n", s[j + 2] - diff);
								if (s[j + 4] == ' '){
									break;
								}
							}
							else if ((s[j + 3] - diff) == 'a'){
								//printf("%c\n", s[j + 2] - diff);
								if ((s[j + 4] - diff) == 't'){
									//printf("%c\n", s[j + 3] - diff);
									if (s[j + 5] == ' '){
										break;
									}
								}
							}
							else if ((s[j + 3] - diff) == 'i'){
								//printf("%c\n", s[j + 2] - diff);
								if ((s[j + 4] - diff) == 's'){
									//printf("%c\n", s[j + 3] - diff);
									if (s[j + 5] == ' '){
										break;
									}
								}
							}

						}
					}
				}
			}
		}
		//printf("diff:%d\n",diff);
		for (int i = 0; i < strlen(s); i++){
			if (s[i] == ' ' || s[i] == '.')continue;
			s[i] -= diff;
		}
		//s[strlen(s) - 1] = '\n';
		printf("%s\n", s);
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <map>
#include <vector>
#include <string>
#include <cstdio>
#include <cmath>

using namespace std;

int main(void)
{
    string s;
    while(getline(cin, s)) {
        for(int i=0; i<26; i++) {
            for(int j=0; j<(int)s.size(); j++) {
                if('a' <= s[j] && s[j] <='z') {
                    s[j] = (s[j] - 'a' + 1) % 26 + 'a';
                }
            }
            if(s.find("the") != string::npos || s.find("this") != string::npos ||
                    s.find("that") != string::npos)
                break;
        }
        cout << s << endl;
    }

    return 0;
}

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] + 1;
	            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;
}