Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		var result string
		line := scanner.Text()
		key := make(map[string]string)

		var i int32
		for ; i < 52; i++ {
			makeKey(key, i)
			result = decode(key, line)

			if strings.Contains(result, "the") {
				break
			} else if strings.Contains(result, "this") {
				break
			} else if strings.Contains(result, "that") {
				break
			}
		}

		fmt.Println(result)
	}
}

func makeKey(key map[string]string, shift int32) {
	for i := 'a'; i <= 'z'; i++ {
		cipher := (i + shift)
		if cipher > 'z' {
			cipher = cipher%'z' + 'a' - 1
		} else if cipher < 'a' {
			cipher = cipher + ('z' - 'a') + 1
		}
		key[string(i)] = string(cipher)
	}
}

func decode(key map[string]string, cipher string) string {
	var result string
	for _, v := range cipher {
		if key[string(v)] != "" {
			result += key[string(v)]
		} else {
			result += string(v)
		}
	}
	return result
}

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 <math.h>

using namespace std;

int main(){

	char buf[81],result[81];
	bool FLG;
	short length;

	while(fgets(buf,81,stdin)!=0){
		FLG = false;
		length = 0;
		for(int i=0;buf[i]!='\0';i++)length++;
		for(int i=0;i<=25;i++){ //?????????????????°
			for(int k=0;buf[k]!='\0';k++){
				if(buf[k] >= 97 && buf[k] <= 122){
					if(buf[k]+i<=122){
						result[k]=buf[k]+i;
					}else{
						result[k]=97+(buf[k]+i-123);
					}
				}else{
					result[k]=buf[k];
				}
				result[k+1]='\0';
			}
			for(int k=0;result[k]!='\0';k++){
				// the this that ????????????????????????????????????
				if(length==4){
					if(result[0]=='t'&&result[1]=='h'&&result[2]=='e'&&result[3]=='.'){
						FLG=true;
						break;
					}
				}else{
					//??????
					if(result[0]=='t'&&result[1]=='h'&&result[2]=='e'&&result[3]==' '){
						FLG=true;
						break;
					}else if(result[0]=='t'&&result[1]=='h'&&result[2]=='i'&&result[3]=='s'&&result[4]==' '){
						FLG=true;
						break;
					}else if(result[0]=='t'&&result[1]=='h'&&result[2]=='a'&&result[3]=='t'&&result[4]==' '){
						FLG=true;
						break;
					}

					//????°?
					if(result[length-1]=='.'&&result[length-2]=='e'&&result[length-3]=='h'&&result[length-4]=='t'&&result[length-5]==' '){
							FLG=true;
							break;
					}
					if(length>5&&result[length-1]=='.'&&result[length-2]=='s'&&result[length-3]=='i'&&
							result[length-4]=='h'&&result[length-5]=='t'&&result[length-6]==' '){
							FLG=true;
							break;
					}else if(length>5&&result[length-1]=='.'&&result[length-2]=='t'&&result[length-3]=='a'&&
							result[length-4]=='h'&&result[length-5]=='t'&&result[length-6]==' '){
							FLG=true;
							break;
					}


					for(int p=4;result[p]!='\0';p++){
						if(result[p]==' ' && result[p-1] == 'e' && result[p-2] == 'h' && result[p-3] == 't' && result[p-4] == ' '){
							FLG = true;
							break;
						}
					}
					if(FLG)break;
					for(int p=5;result[p]!='\0';p++){
						if(result[p]==' ' && result[p-1] == 's' && result[p-2] == 'i' && result[p-3] == 'h' && result[p-4] == 't' && result[p-5] == ' '){
							FLG = true;
							break;
						}
					}
					if(FLG)break;
					for(int p=5;result[p]!='\0';p++){
						if(result[p]==' ' && result[p-1] == 't' && result[p-2] == 'a' && result[p-3] == 'h' && result[p-4] == 't' && result[p-5] == ' '){
							FLG = true;
							break;
						}
					}
					if(FLG)break;
				}
			}
			if(FLG)break;
		}
		printf("%s",result);

	}

    return 0;
}

C++: //include
 //------------------------------------------
 #include <vector>
 #include <list>
 #include <map>
 #include <set>
 #include <deque>
 #include <stack>
 #include <bitset>
 #include <algorithm>
 #include <functional>
 #include <numeric>
 #include <utility>
 #include <sstream>
 #include <iostream>
 #include <iomanip>
 #include <cstdio>
 #include <cmath>
 #include <cstdlib>
 #include <cctype>
 #include <string>
 #include <cstring>
 #include <ctime>

 using namespace std;

 //conversion
 //------------------------------------------
 inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
 template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

 //math
 //-------------------------------------------
 template<class T> inline T sqr(T x) {return x*x;}

 //typedef
 //------------------------------------------
 typedef vector<int> VI;
 typedef vector<VI> VVI;
 typedef vector<string> VS;
 typedef pair<int, int> PII;
 typedef long long LL;
 typedef unsigned long long ULL;

 //container util
 //------------------------------------------
 #define ALL(a)  (a).begin(),(a).end()
 #define RALL(a) (a).rbegin(), (a).rend()
 #define PB push_back
 #define MP make_pair
 #define SZ(a) int((a).size())
 #define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
 #define EXIST(s,e) ((s).find(e)!=(s).end())
 #define SORT(c) sort((c).begin(),(c).end())

 //repetition
 //------------------------------------------
 #define FOR(i,a,b) for(int i=(a);i<(b);++i)
 #define REP(i,n)  FOR(i,0,n)

 //constant
 //--------------------------------------------
 const double EPS = 1e-10;
 const double PI  = acos(-1.0);

 //clear memory
 #define CLR(a) memset((a), 0 ,sizeof(a))

 //debug
 #define dump(x)  cerr << #x << " = " << (x) << endl;
 #define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

 int main() {
   int n;
   string str;

   while(getline(cin, str)) {
     for(int i = 0; i < str.size(); i++) {
       for(int j = 0; str[i]+j <= 'z'; j++) {
	 if(str[i] + j == 't' && str[i+1] + j == 'h') {
	   n = j;
	   break;
	 }
       } 
       for(int j = 0; str[i]-j >= 'a'; j++) {
	 if(str[i] - j == 't' && str[i+1] - j == 'h') {
	   n = -j;
	 break;
	 }
       }
     }
     
     for(int i = 0; i < str.size(); i++) {
       if(str[i] == ' ' || str[i] == '.' || str[i] == '\n') printf("%c", str[i]);
       else printf("%c", str[i]+n);
     }
     cout << endl;
   }
 }

C++: #include <iostream>
#include <string>

using namespace std;

int main(int argc, const char * argv[])
{
    int shift = 0, i=0;
    string in,out;
    getline(cin,in);
    out = in;
    do {
        for (i=0; i<in.length(); i++) {
            if (in[i]!=' '&&in[i]!='.') {
                out[i] = ((in[i] - 'a' + shift) % 26) + 'a';
            }
        }
        if (out.find("the")!=std::string::npos||out.find("that")!=std::string::npos||out.find("this")!=std::string::npos) {
            break;
        }
        else
            shift++;
    } while (1);
    
    cout<<out;
    return 0;
}