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

C++: #include<iostream>
#include<string>
#include<string.h>
using namespace std;
int main()
{
	string s;
	while (getline(cin, s)){
		while (true){
			for (int i = 0; i < s.size(); i++){
				if (s[i] == 'z'){
					s[i] = 'a';
				}
				else if (s[i] != ' '&&s[i] != '.'){
					s[i]++;
				}
			}
			if (s.find("the") != -1)break;
			if (s.find("this") != -1)break;
			if (s.find("that") != -1)break;
		}
		cout << s << endl;
	}
}

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

using namespace std;

int main(int argc, char *argv[]) {
  string str;
  vector<string> result;
  while (getline(cin, str)) {
    while (true) {
      if (str.find(" this ") != string::npos ||
          str.find(" that ") != string::npos ||
          str.find(" the ") != string::npos)
        break;
      else
        for (int i = 0; i < str.size(); i++)
          if ('a' <= str[i] && str[i] <= 'z') {
            if (str[i] == 'a')
              str[i] = 'z';
            else
              str[i]--;
          }
    }
    cout << str << endl;
  }
  return 0;
}

C++: //
// Created by Tian Wang on 16/4/3.
//
#include <iostream>
#include <string>
#include <vector>

using namespace std;

bool ascii_diff(string x1, string x2) {
    int len = x1.size();
    bool flag = true;
    for(int i = 1; i < len; i++) {
        int diff1 = (int)x1[i] - (int)x1[i-1];
        int diff2 = (int)x2[i] - (int)x2[i-1];
        if(diff1 != diff2) {
            flag = false;
        }
    }
    return flag;
}

int main() {
    string str1 = "the";
    string str2 = "this";
    string str3 = "that";
    string x;
    int len, len_whole;
    int diff=0;
    string word;
    int word_len;
    int sent_len;
    int ascii;
    char k;
    vector<string> input;
    bool new_line_flag = false;

    for(string line; getline(cin, line);) {
        len_whole = line.size();
        string x1;
        for(int i = 0; i < len_whole; i++) {
            k = line[i];

            if((int)k >= 97 & (int)k <=122) {
                x1.push_back(k);
            }
            else {
                input.push_back(x1);
                x1.clear();
                x1.push_back(k);
                input.push_back(x1);
                x1.clear();
            }
        }
        x1.clear();
        sent_len = input.size();
        for(int i =0; i < sent_len; i++) {
            x = input[i];
            len = x.size();
            if(len == 3) {
                if(ascii_diff(str1, x)) {
                    diff = (int)x[0] - (int)str1[0];
                }
            }
            else if(len == 4) {
                if(ascii_diff(str2, x)) {
                    diff = (int)x[0] - (int)str2[0];
                }
                else if (ascii_diff(str3, x)) {
                    diff = (int)x[0] - (int)str3[0];
                }
            }
        }
        for(int i = 0; i < sent_len; i++) {
            word = input[i];
            word_len = word.size();
            for(int j = 0; j < word_len; j++) {
                ascii = (int)word[j];
                if(ascii >= 97 & ascii <=122) {
                    cout << (char)(ascii-diff);
                }
                else {
                    cout << (char)ascii;
                }
            }
        }
        cout << endl;
        input.clear();
    }
    return 0;




/**
    while(cin >> noskipws >> x) {
        cout << x << endl;

        input.push_back(x);
        len = x.size();
        if(x.back() == '\n') {
            x.pop_back();
            new_line_flag = true;
        }
        if((int)x.back() < 97 | (int)x.back() > 122 ) {
            x.pop_back();
        }
        if(len == 3) {
            if(ascii_diff(str1, x)) {
                diff = (int)x[0] - (int)str1[0];
            }
        }
        else if(len == 4) {
            if(ascii_diff(str2, x)) {
                diff = (int)x[0] - (int)str2[0];
            }
            else if (ascii_diff(str3, x)) {
                diff = (int)x[0] - (int)str3[0];
            }
        }
        if(new_line_flag) {
            new_line_flag = false;
            break;
        }
    }
    int input_size = input.size();
    for(int i = 0; i < input_size; i++) {
        word = input[i];
        word_len = word.size();
        for(int j = 0; j < word_len; j++) {
            ascii = (int)word[j];
            if(ascii >= 97 & ascii <=122) {
                cout << (char)(ascii-diff);
            }
            else {
                cout << (char)ascii;
            }
        }
        if(i != input_size-1) {
            cout << " ";
        }
        else{
            cout <<endl;
        }
    }
    return 0;
    **/
}

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

bool find( string a, string b )                         //文字列aの中に、bが含まれているかどうか判定する関数
{
    for( int i = 0; i <= a.size() - b.size(); i++ )
    {
        int j = i, k = 0;
        while( k < b.size() )
        {
            if( a[j] == b[k] )
            {
                j++;
                k++;
            }
            else
                break;
        }
        if( k == b.size() )
            return true;
    }
    return false;
}

int main()
{
    string cipher;
    string cand;

    int i = 0;                                               //cand[24]まで順にずらした文字列を順に格納
    while ( getline( cin, cipher ) )
    {
        for( int k = 1; k < 26; k++ )
        {
            cand = "";
            for( int j = 0; j < cipher.size(); j++, i++ )    //candに文字列を入れる操作
            {
                if( cipher[j] == ' ' )
                    cand += " ";
                else if( cipher[j] == '.' )
                    cand += ".";
                else
                    cand += 97 + ( cipher[j] + k ) % 26;     //cipherの文字列を順にずらして、candに格納
            }
            if( find( cand, "this" ) == true || find( cand, "that" ) == true || find( cand, "the" ) == true )
                cout << cand << endl;
        }
    }
    return 0;
}