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>
#include <cstdio>
#include <algorithm>

using namespace std;

int main(){
	
	char c[2000];
	
	bool checker;
	
	while(true){
		
		if(cin.eof()){
			break;
		}
		
		gets(c);
		
		for(int i = 0; i < 26; i++){
			for(int j = 0; j < 2000; j++){
				if(c[j] == '\0'){
					break;
				}else if(c[j] == 'z'){
					c[j] = 'a';
				}else if(c[j] == ' '){
					c[j] = ' ';
				}else if(c[j] == '.'){
					c[j] = '.';
				}else{
					c[j]++;
				}
			}
			
			checker = false;
			
			for(int j = 0; j < 2000; j++){
				if(c[j] == '\0'){
					break;
				}
				if(c[j] == 't' && c[j + 1] == 'h'){
					if(c[j + 2] == 'e'){
						checker = true;
						break;
					}else if(c[j + 2] == 'i' && c[j + 3] == 's'){
						checker = true;
						break;
					}else if(c[j + 2] == 'a' && c[j + 3] == 't'){
						checker = true;
						break;
					}
				}
			}
			
			if(checker){
				break;
			}
		}
		
		for(int i = 0; i < 2000; i++){
			if(c[i] == '\0'){
				break;
			}
			cout << c[i];
		}
		cout << endl;
	}
	
	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <stack>
#include <cmath>
using namespace std;

#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define llong long long

int main() {
  char *a = (char*)malloc(sizeof(char)*82);
  size_t l = 0;
  while (getline(&a, &l, stdin) != EOF) {
    while(1) {
      int q = 0;//-1..out, 0..space, 1..t, 2..th, 3..the, 4...thi, 5..this, 6..tha, 7..that, 8..ok
      REP(j , (int)l-1) {
	if(a[j] == 'z') a[j] = 'a';
	else if(a[j] >= 'a' && a[j] < 'z') a[j]++;
      }
      REP(j , (int)l-1) {
	switch(q){
	case -1:
	  if(a[j] == ' ') q = 0;
	  break;
	case 0:
	  if(a[j] == 't') q = 1;
	  else q = -1;
	  break;
	case 1:
	  if(a[j] == 'h') q = 2;
	  else q = -1;
	  break;
	case 2:
	  if(a[j] == 'e') q = 3;
	  else if(a[j] == 'i') q = 4;
	  else if(a[j] == 'a') q = 6;
	  else q = -1;
	  break;
	case 3:
	  if(a[j] > 'z' || a[j] < 'a') q = 8;
	  else q = -1;
	  break;
	case 4:
	  if(a[j] == 's') q = 5;
	  else q = -1;
	  break;
	case 5:
	  if(a[j] > 'z' || a[j] < 'a') q = 8;
	  else q = -1;
	  break;
	case 6:
	  if(a[j] == 't') q = 7;
	  else q = -1;
	  break;
	case 7:
	  if(a[j] > 'z' || a[j] < 'a') q = 8;
	  else q = -1;
	  break;
	}
      }
      if(q == 8) break;
    }
    
    REP(i , (int)l-1) {
      printf("%c",a[i]);
    }
  }
  return 0;
}

C++: #include<string>
#include<iostream>
#include<algorithm>
using namespace std;
string henkan(string a)
{
	for (int i = 0; i < a.size(); i++)
	{
		if (a[i] != ' '&&a[i] != '.')
		{
			if (a[i] == 'z')a[i] = 'a';
			else 
				a[i] += 1;
		}
	}
	return a;
}
bool check(string a)
{
	string x[3] = { "the", "this", "that" };
	for (int i = 0; i < 3; i++)
	{
		if (a.find(x[i], 0) != string::npos)return false;
	}
	return true;
}
int main()
{
	string a, b;
	cin >> b;
	a.append(b);
	while (b.find('.', 0) == string::npos)
	{
		a.append(" ");

		cin >> b;
		a.append(b);
	}
	while (check(a))
	{
		a=henkan(a);
	}
	cout << a << endl;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main(void){

    for(;;){
        string a;
        bool flg=0;
        while(getline(cin,a)){
            if(a[0]==EOF)flg=1;break;

            for(int i=0;i<26;i++){
                if(a.find("the")!=string::npos||a.find("this")!=string::npos||a.find("that")!=string::npos){
                    cout<<a<<endl;break;
                }
                else
                    for(int i=0;i<a.length();i++){
                        if(a[i]>='a'&&a[i]<='y')a[i]++;
                        else if(a[i]=='z')a[i]='a';
                    }
            }
        }
    }
    return 0;
}

C++: #include<iostream>
#include<string.h>
#include<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#define li long long int
#define ld long long double
#define PI 3.1415926535897932384626
#define EPS 0.0000000001
#define rep(i,n) for(i=0;i<n;i++)
using namespace std;
typedef pair<int, int> P;

string str;
char word[3][5]={"the","this","that"};
char sent[80][80]={};
int main()
{
  bool ans=false;
  while(getline(cin,str)){
    int i=0,j=0;
    if(str.size()==0)break;
   // scanf("%*c");
    int num=0;
    for(i=0;num<str.size();i++){
      for(j=0;;j++){
	sent[i][j]=str[num];
	num++;
	if(sent[i][j]==' '){
	  sent[i][j]='\0';
	  break;
	}
	if(sent[i][j]=='\0')break;
      }
    }
    //cout<<i<<endl;
    int gap,k,l;
    
    rep(gap,26){
      rep(k,i) rep(l,strlen(sent[k])){
	if(sent[k][l]>='a' && sent[k][l]<'z')
	   sent[k][l]++;//??????????????????
	else if(sent[k][l]=='z')
	  sent[k][l]='a';
      	//cout<<sent[k][l];//debug
      }
      // cout<<endl;//debug
      rep(k,i)
	if(strcmp(sent[k],word[0])==0 || strcmp(sent[k],word[1])==0 
	   || strcmp(sent[k],word[2])==0){
	  rep(l,i){
	    for(int a=0;a<strlen(sent[l]);a++)
	      cout<<sent[l][a];
	    if(l<i-1)
	      cout<<" ";
	    else
	      cout<<endl;
	  }
	  ans=true;
	  break;
	}
      if(ans)break;
    }
  }
}

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 = 0;
		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++: #include<iostream>
#include<cstring>
#include<sstream>
using namespace std;
/*
string text = "hello world";
stringstream ss(text);
string t;
while (ss >> t){
*/
void fin(string a)
{
	cout << a << endl;
	return;
}
int main()
{
	string a,b;
	bool fir=false;
	while (cin >> b)
	{
		if(fir)a.append(" ");
		a.append(b);
		fir = true;
	}
	while (1)
	{
		if (a.find("the", 0) != string::npos)
		{
			fin(a); return 0;
		}
		if (a.find("this", 0) != string::npos)
		{
			fin(a); return 0;
		}
		if (a.find("that", 0) != string::npos)
		{
			fin(a); return 0;
		}
		for (int i = 0; i < a.size(); i++)
		{
			if (a[i] != ' '&&a[i]!='.')a[i] += 1;
			if (a[i]>'z')a[i] = 'a';
		}
	}
	

}