Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

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 scanner.Scan() {
		infos := strings.Split(scanner.Text(), " ")
		plain := make([]string, len(infos))
		// fmt.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 <iomanip>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <sstream>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <numeric>
#include <cmath>
#include <climits>
#include <limits>
#include <cfloat>
#include <fstream>
using namespace std;

int main()
{
	const string key[] = { "the", "this", "that" };
//	cut here before submit 
//	freopen("testcase.cc", "r", stdin);
	string str = "";
	
	while (getline (cin, str )){
		int len = str.length();
		int i,j;
		vector <bool> match (3, false);
		for (j = 0; j < 26; ++j){
			string curr = str;
			for (i = 0; i < len; ++i){
				if ( isalpha(curr[i]) ){
					curr[i] = (curr[i] - 'a' + 26 - j) % 26 + 'a';
				} // end if
			} // end for
			
			for (i = 0; i < 3; ++i){
				if ( curr.find(key[i]) != string::npos ){
					match[i] = true;
				} // end if
			} // end for
			if ((int)count(match.begin(), match.end(), true ) == 3){
				cout << curr << endl;
				break;
			} // end if
		} // end for
	} // end while
		
	return 0;
}

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

using namespace std;

int main()
{
	string S[80]; int C = 0;

	while (getline(cin, S[C]))
	{
		C++;
	}

	for (int i = 0; i < 26; i++)
	{
		for (int c = 0; c < C; c++)
		{
			if (!(S[c].find("this") == string::npos && S[c].find("that") == string::npos && S[c].find("the") == string::npos))
			{
				for (int j = 0; j < C; j++) { cout << S[j] << endl; }

				goto Exit;
			}

			for (string::size_type j = 0; j < S[c].size(); j++)
			{
				if (isalpha(static_cast<int>(S[c][j])))
				{
					if (S[c][j] == 'z')
					{
						S[c][j] = 'a';
					}
					else
					{
						S[c][j]++;
					}
				}
			}
		}
	}

Exit:;

	return 0;
}

C++: #include <iostream>
#include <string>
//#include <string.h>
using namespace std;
int main(){
	char alpha[] = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
	string str;
	while( 1 ){
		if( getline( cin, str ).eof() ) break;
		for( int a = 0; a < 26; a++ ){
			for( size_t i = 0; i < str.length(); i++ ){
				for( size_t j = 0; j < sizeof(alpha); j++ ){
					if( str[i] == alpha[j] ){
						str[i] = alpha[j + 1];
						break;
					}
				}
			}
			if( str.find("the") != string::npos || str.find("this") != string::npos || str.find("that") != string::npos ){
				break;
			}
		}
		cout << str << endl;
	}
}

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

using namespace std;


int main(){
	string line;

	while(getline(cin, line)){
		int flag = 0;

		for(int i=0 ; i<26 ; i++){
			for(int j=0 ; j<line.size() ; j++){
				if(line[j] != ' ' && line[j] != '.'){
					if(line[j] == 'a'){
						line[j] = 'z' ;
					}else{
						line[j]--;
					}
				}
			}

			for(int k=0 ; k<line.size()-2 ; k++){
				if(line[k] == 't' && line[k+1] == 'h'){
					flag = 1;
					cout << line << endl;
					break;
				}
			}
			if(flag == 1) break;
			cout << line << endl;
		}
		//cout << line << endl;
	}
	return 0;
}

C++: #define _USE_MATH_DEFINES

#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <numeric>

using namespace std;

int caesar(string s)
{
	string s0 = "this";
	string s1 = "that";
	string s2 = "the";

	if (s.size() > 4)
	{
		return -1;
	}

	for (int i = 0; i <= 26; i++)
	{
		if (s == s0 || s == s1 || s == s2)
		{
			return i;
		}
		for (int j = 0; j < 4; j++)
		{
			s0.at(j) = s0.at(j)++;
			if (s0.at(j) > 'z')
			{
				s0.at(j) = 'a';
			}
			s1.at(j) = s1.at(j)++;
			if (s1.at(j) > 'z')
			{
				s1.at(j) = 'a';
			}
		}
		for (int j = 0; j < 3; j++)
		{
			s2.at(j) = s2.at(j)++;
			if (s2.at(j) > 'z')
			{
				s2.at(j) = 'a';
			}
		}
	}

	return -1;
}

int main()
{
	string str;
	for (; getline(cin, str);)
	{
		stringstream ss;
		ss << str;

		vector<string> w;
		string s;
		int c = -1;
		for (; ss >> s;)
		{
			w.push_back(s);
			
			if (c == -1)
			{
				c = caesar(s);
			}
		}

		for (int i = 0; i < w.size(); i++)
		{
			for (int j = 0; j < w.at(i).size(); j++)
			{
				if (w.at(i).at(j) != '.')
				{
					char sp = w.at(i).at(j) - c;
					if (sp < 'a')
					{
						int p = 'a' - sp;
						w.at(i).at(j) = 'z' - p;
					}
					else
					{
						w.at(i).at(j) = sp;
					}
				}			
			}

			cout << w.at(i) << (i == w.size() - 1 ? "" : " ");
		}

		cout << endl;
	}
}

C++: #include <iostream>
#include <string.h>
#include <string>
#include <stdio.h>
using namespace std;
int main() {
	char st[81];
	string w[3]={"the","this","that"};
	int wn[3]={3,4,4},k,i,j,s,f,z;
	while(true) {
    k=0; z=0;
	scanf("%81[a-z. \n]",st);
	z=strlen(st);
	while(k<z) {
		for (i=0;i<3;i++) {
			s=0; f=0;
			if (z<=k+wn[i]) break;
			for (j=0;j<wn[i]-1;j++) if ((w[i][j]-w[i][j+1])==(st[k+j]-st[k+j+1])) s++;
			if (s==wn[i]-1 && (st[k+wn[i]]<'a' || st[k+wn[i]]>'z' ))  { f=1; i=5;}
		}
		if (f==1) break;
		for (k;st[k]>='a' && st[k]<='z';k++);
		k++;
		}
	if (f==0) cout << st; else {
	for (i=0;i<z;i++) if ((st[i]>='a' && st[i]<='z')) cout << (char)(st[i]-(st[k]-'t')) ; else cout << st[i];
	  }	
	}
    return 0;
	}