Go: package main

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

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 reflect.DeepEqual(infos, []string{}) {
			break
		}
		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<string>
#include<sstream>
#include<vector>
using namespace std;
#define REP(i, j) for(int i = 0; i < j; i++)
#define FOR(i, j, k) for(int i = j; i < k; i++)
const int N = 30;

bool isOK(vector<string> v){
    REP(i, v.size()) if(v[i] == "the" || v[i] == "this" || v[i] == "that") return true;
    return false;
}

int main(){
    string str;
    while(getline(cin, str)){
        str = str.substr(0, str.length() - 1);
        string tmp;
        stringstream ss(str);
        vector<string> v;
        while(ss >>tmp) v.push_back(tmp);
        REP(z, N){
            REP(i, v.size()) REP(j, v[i].length()) v[i][j] = ++v[i][j] <= 'z'? v[i][j] : 'a';
            if(isOK(v)){
                cout <<v[0];
                FOR(i, 1, v.size()) cout <<" " <<v[i];
                cout <<'.' <<endl;
                break;
            }
        }
    }
    return 0;
}

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

int main(){
	stirng s;
	while(getline(cin,s)){
		while(s.find("the") == string::npos
				&& s.find("this") == string::npos
				&& s.find("that") == string::npos){
					for(int i = 0; i < s.size(): i++){
						if(s[i] == 'z')
							s[i] = 'a';
						else if(s[i] >= 'a' && s[i] <= 'z')
							s[i]++;
					}
				}
		cout << s << endl;		
	}
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

int main(){
	char input[100],str[50][100];
	const char cmp[3][5]={"that","this","the"};
	int pos=0,last_pos=0,i,j,k,diff,n;
	bool flag;

		fgets(input,100,stdin);
		for(i=0;input[i]!='\0';i++){
			if(input[i]==' ' || input[i]=='.' || input[i]=='\n'){
				for(j=last_pos;j<i;j++){
					str[pos][j-last_pos]=input[j];
				}
				str[pos][j-last_pos]='\0';
				pos++;
				last_pos=i+1;
			}
		}

		n=0;
		flag=false;
		while(++n){
			for(i=0;i<pos;i++){
				for(j=0;str[i][j]!='\0';j++){
					str[i][j]+=1;
					if('a'>str[i][j]){
						str[i][j]+='z'-'a'+1;
					}else if('z'<str[i][j]){
						str[i][j]+='a'-'z'-1;
					}
				}
			}

			for(i=0;i<pos;i++){
				for(j=0;j<3;j++){
					if(strcmp(str[i],cmp[j])==0){
						flag=true;
                        j=3;i=pos;
					}
				}
			}
			if(flag) break;
		}

		int temp;
		for(i=0;input[i]!='\n';i++){
			if(input[i]!='.' && input[i]!=' '){
				temp=input[i]+n;
				if('a'>temp){
					input[i]=temp+'z'-'a'+1;
				}else if('z'<temp){
					input[i]=temp+'a'-'z'-1;
				}else{
					input[i]=temp;
				}
			}
		}
		printf("%s",input);

	return 0;
}

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

using namespace std;

string slide(string s) {
  string r = s;
  for (int i = 0; i < r.length(); i++) {
    if (islower(r[i])) {
      if (r[i] == 'z') r[i] = 'a';
      else r[i] += 1;
    }
  }
  return r;
}

bool check_word(string s) {
  string dic[3] = {"this", "the", "that"};
  stringstream ss;
  string word;
  ss << s;
  for (int i = 0; i < 3; i++) {
    ss >> word;
    if (dic[i] == word) return true;
  }
  return false;
}

int main() {
  string in, temp;
  bool found;
  while (!cin.eof()) {
    getline(cin, in);
    for (temp = in, found = false; ; temp = slide(temp)) {
      found = check_word(temp);
      if (found) break;
    }
    cout << temp << endl;
  }
  return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <ctype.h>

using namespace std;

inline char rotate(char c, int x){
    int r = x % 26;
    if(isalpha(c)){
        c += r;
    }

    return c;
}

inline char decode_from_t(char t, char tgt){
    int df = ('t' - t) % 26;
    tgt += df;
    return tgt;
}

char buf[82];
enum state {
    init,
    wait_h,
    after_th,
    rest_chars,
    wait_sep,
    other_word,
};

inline bool is_sep(char *c){
    return *c == '.' || *c == ' ';
}

// return diff.
int findTheThatThis(){
    state s = init;
    char *c = buf;
    char next, dec, t;

    while(*c != '\n'){
        switch (s) {
            case init:
                if(isalpha(*c)){
                    s = wait_h;
                    t = *c;
                }
                break;
            case wait_h:
                if(is_sep(c)){
                    s = init;
                }else{
                    dec = decode_from_t(t, *c);
                    if(dec == 'h'){
                        s = after_th;
                    }else{
                        s = other_word;
                    }
                }
                break;
            case after_th:
                if(is_sep(c)){
                    s = init;
                }else {
                    dec = decode_from_t(t, *c);
                    switch (dec) {
                        case 'e':
                            s = wait_sep;
                            break;
                        case 'i':
                            next = 's';
                            s = rest_chars;
                            break;
                        case 'a':
                            next = 't';
                            s = rest_chars;
                            break;
                        default:
                            s = other_word;
                            break;
                    }
                }
                break;
            case rest_chars:
                if(is_sep(c)){
                    s = init;
                }else{
                    dec = decode_from_t(t, *c);
                    if(dec == next){
                        s = wait_sep;
                    }else{
                        s = other_word;
                    }
                }
                break;
            case wait_sep:
                if(is_sep(c)){
                    return 't' - t;
                }else{
                    s = other_word;
                }
                break;
            case other_word:
                if(is_sep(c)){
                    s = init;
                }
                break;
        } // end switch
        c++;
    } // end while
    // not found
    return -1;
}

int main(int argc, char const* argv[])
{
    int dif;

    while (nullptr != fgets(buf, 82, stdin)) {
        dif = findTheThatThis();
        for (int i = 0; ; i++) {
            if(buf[i] == '\n'){
                buf[i] = '\0';
                puts(buf);
                break;
            }
            buf[i] = rotate(buf[i], dif);
        }
    }

        return 0;
}