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<cstdio>
#include<iostream>
#include<cstring>

using namespace std;
int key;

int dist(char s1,char s2){
 
  if(s1==s2){
    return 0;
  }else if(s1<s2){
    return s2-s1;
  }else{
    return 'z'-s1+s2-'a'+1;
  }
}

bool checkThe(char s[]){
  if(strlen(s)!=3){
    return false;
  }else{
    if(dist('t',s[0])==dist('h',s[1]) && dist('h',s[1])==dist('e',s[2])){
      key=dist('t',s[0]);
      return true;
    }
  }
  return false;
}
bool checkThis(char s[]){
  if(strlen(s)!=4){
    return false;
  }else{
    if(dist('t',s[0])==dist('h',s[1]) && dist('h',s[1])==dist('i',s[2]) && dist('i',s[2])==dist('s',s[3])){
      key=dist('t',s[0]);
      return true;
    }
  }
  return false;
}
bool checkThat(char s[]){
  if(strlen(s)!=4){
    return false;
  }else{
    if(dist('t',s[0])==dist('h',s[1]) && dist('h',s[1])==dist('a',s[2]) && dist('a',s[2])==dist('t',s[3])){
      key=dist('t',s[0]);
      return true;
    }
  }
  return false;

}
int main(){
 
  char str[100];
  char temp[100];
 
  char *tok;
  bool f;
  while(fgets(str,sizeof(str),stdin)!=NULL){
    key=0;
    f=false;
    for(int i=0;i<strlen(str);i++)
      temp[i]=str[i];
    temp[strlen(str)]='\0';

    str[strlen(str)]='\0';
    str[strlen(str)-1]='\0';
    tok=strtok(str," ");
 
    if(strlen(tok)==3){
      if(checkThe(tok)==true){
	f=true;
      }
    }else if(strlen(tok)==4){
      if(checkThat(tok)==true){
	f=true;
      }else if(checkThis(tok)==true){
	f=true;
      }
    }
    while(f==false && tok!=NULL){
      tok=strtok(NULL," ");
      if(tok!=NULL){
	if(strlen(tok)==3){
	  if(checkThe(tok)==true){
	    f=true;
	  }
	}else if(strlen(tok)==4){
	  if(checkThat(tok)==true){
	    f=true;
	  }else if(checkThis(tok)==true){
	    f=true;
	  }
	}
      }
    }
 
   
    for(int i=0;i<strlen(temp);i++){
      if('a'<=temp[i] && temp[i]<='z'){
	if(temp[i]-key>'z'){
	  printf("%c",(temp[i]-key));
	}else if(temp[i]-key<'a'){
	  printf("%c",(temp[i]-key)+26);
	}else{
	  printf("%c",(temp[i]-key));
	}
      }else{
	printf("%c",temp[i]);
      }
    }

  }

  return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<sstream>
int main()
{
	std::vector<std::string>result;
	for (std::string s; std::getline(std::cin, s);)
	{
		int delta;
		std::stringstream ss;
		ss << s;
		while (!ss.eof())
		{
			std::string temp;
			ss >> temp;
			if (temp.length() == 3 && temp[0] != '.' && temp[1] != '.' && temp[2] != '.')
			{
				int d1 = temp[0] - temp[1];
				int d2 = temp[1] - temp[2];
				if (d1 == 't' - 'h' && d2 == 'h' - 'e')
				{
					delta = temp[0] - 't';
					break;
				}
			}
			else if (temp.length() == 4 && temp[0] != '.' && temp[1] != '.' && temp[2] != '.' && temp[3] != '.')
			{
				int d1 = temp[0] - temp[1];
				int d2 = temp[1] - temp[2];
				int d3 = temp[2] - temp[3];
				if (d1 == 't' - 'h' && (d2 == 'h' - 'i' && d3 == 'i' - 's' || d2 == 'h' - 'a' && d3 == 'a' - 't'))
				{
					delta = temp[0] - 't';
					break;
				}
			}
		}
		result.push_back(std::string(s.length(), 'a'));
		for (int i = 0; i < s.length(); i++)
		{
			result.back()[i] = s[i] != '.' && s[i] != ' ' ? (s[i] - delta - 'a') % 26 + 'a' : s[i];
		}
	}
	for (auto i : result)
	{
		std::cout << i << std::endl;
	}
	return 0;
}

C++: //#define _USE_MATH_DEFINES
//#include <cmath>
#include <iostream>
//#include <stdio.h>
//#include <stdlib.h>
//#include <iomanip>
#include <vector>
#include <string>
//#include <algorithm>
//#include <functional>
//#include <time.h>
#include <sstream>

using namespace std;

bool isthe(string str){
	//?????????????????????????????? the this that?????¢??? ????????°ture

	int d1, d2, d3;

	d1 = (str[1] - str[0] + 26) % 26;

	if (d1 != 14){
		return false;
	}
	else{
		d2 = (str[2] - str[0] + 26) % 26;
		if (d2 != 11 && d2 != 15 && d2 != 7){
			return false;
		}
		else{
			if (d2 == 11 && str.size() == 3){
				return true;
			}
			else{
				d3 = (str[3] - str[0] + 26) % 26;
				if (d2 == 15 && d3 == 25) return true;
				if (d2 == 7 && d3 == 26) return true;
			}
		}
	}

	return false;

}


int main(){
	
	string s,sc, buf;
	stringstream ss;
	vector <string> as;
	int dif = 0;


	while (getline(cin, s)){
		dif = 0;
		buf = "";
		sc = "";
		ss.str("");
		ss.clear();

		sc += s;
		for (int i = 0; i < sc.size(); i++){
			if (sc[i] == '.')sc[i] = ' ';
		}
		ss << sc;

		while (ss >> buf){
			//the this that???????´¢
			if (buf.size() == 3 || buf.size() == 4){
				if (isthe(buf)){
					dif = (buf[0] - 't' + 26)%26;
					break;
				}
			}
		}

		for (int i = 0; i < s.size(); i++){
			if (s[i] >= 'a' && s[i] <= 'z') {
				s[i] -= dif;
				if (s[i] < 'a') s[i] += 26;
				if (s[i] > 'z') s[i] -= 26;
			}
		}

		cout << s << endl;
	}




	return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define INF INT_MAX/3
#define ALL(a) (a).begin(),(a).end()
#define CLR(a) memset(a,0,sizeof(a))

typedef long long int ll;

using namespace std;

int main(){

    string s[] = {"this","the","that"};
    string in;
    while(true){
	getline(cin,in);
	if(cin.eof()) break;
	bool f = false;
	int d = 1;
	REP(i,30){

	    f = true;
	    REP(i,in.size()){
		if(in[i] == '.' || in[i] == ' ') continue;
		in[i]= (char)( 'a' + ( (int)(in[i] - 'a') + d) % 28);
	    }
	    vector<bool> flgs(3,false);
	    for(int i=0;i<in.size();i++){
		REP(j,3){
		    if(in.substr(i,s[j].size()) == s[j]) flgs[j] = true;
		}
	    }
	    if(flgs[0] && (flgs[1] || flgs[2])) break;
	}
	cout << in << endl;
    }

    return 0;
}

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

using namespace std;

int main()
{
  string stro, str;
  while(getline(cin, stro)){
    for(int i = 1; i < 26; i++){
      str = stro;
      for(int j = 0; j < stro.length(); j++){
	if(str[j] != ' ' && str[j] != '.' && str[j] != '\n')
	  if(str[j] + i > 'z')
	    str[j] += i - 26;
	  else
	    str[j] += i;
      }
      unsigned f_the = str.find("the", 0);
      unsigned f_this = str.find("this", 0);
      unsigned f_that = str.find("that", 0);
      if((f_the != string::npos && (str[f_the - 1] == ' ' || str[f_the - 1] == '.' || str[f_the - 1] == '\n') && (str[f_the + 3] == ' ' || str[f_the + 3] == '.' || str[f_the + 3] == '\n')) || (f_this != string::npos && (str[f_this - 1] == ' ' || str[f_this - 1] == '.' || str[f_this - 1] == '\n') && (str[f_this + 4] == ' ' || str[f_this + 4] == '.' || str[f_this + 4] == '\n')) || (f_that != string::npos && (str[f_that - 1] == ' ' || str[f_that - 1] == '.' || str[f_that - 1] == '\n') && (str[f_that + 4] == ' ' || str[f_that + 4] == '.' || str[f_that + 4] == '\n')))
	cout << str << endl;	
    }
  }
}