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 <stdio.h>
#include <string.h>
#include <math.h>
#include <algorithm>
#include <stdlib.h>
#include <vector>

using namespace std;


int main(){

	string line;

	while(getline(cin, line)){

		string str[80], ans[80];
		int count = 0;
		int flag = 0;
		int slide;

		//???????????????
		/*
		string temp;
		for(int i=0 ; i<line.size()-1 ; i++){
			temp += line[i];
		}
		line = temp;
		*/

		//???????????????????????¨???????´?
		for(int i=0 ; i<line.size() ; i++){
			if(line[i] == ' '){
				count++;
			}else{
				str[count] += line[i];
				ans[count] = str[count];
			}
		}
		count++;


		for(int i=1 ; i<=26 ; i++){
			for(int j=0 ; j<count ; j++){
				for(int k=0 ; k<str[j].size() ; k++){
					if(str[j][k] != '.'){
						str[j][k]++;
						if(str[j][k] > 'z'){
							str[j][k] = str[j][k] - 'z' + 'a' -1;
						}
					}
					if(str[j][k] == 'h' && str[j][k-1] == 't'){
						flag = 1;
						slide = i;
						break;
					}
				}

				/*
				if(str[j] == "this" || str[j] == "the" || str[j] == "that"
						|| str[j] == "this." || str[j] == "the." ||str[j] == "that."){
					flag = 1;
					slide = i;
					break;
				}
				*/
			}
			if(flag == 1)break;
		}

		for(int i=0 ; i<count ; i++){
			for(int j=0 ; j<ans[i].size() ; j++){
				if(ans[i][j] != '.'){
					if((ans[i][j] + slide) > 'z' ){
						ans[i][j] = ans[i][j] - 'z' + 'a' + slide -1;
					}else{
						ans[i][j] = ans[i][j] + slide ;
					}
				}
			}
		}

		for(int i=0 ; i<count ; i++){
			cout << ans[i] << ' ';
		}
		cout << ans[count] << endl;

	}
	return 0;
}

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

using namespace std;

string
caesar (string str, int n)
{
  const string table = "abcdefghijklmnopqrstuvwxyz";
  string ans (str.length (), ' ');
  for (int i = 0; i < str.length (); i++)
    {
      int buf = table.find (str[i]);
      if (buf == string::npos)
	{
	  ans[i] = str[i];
	}
      else
	{
	  ans[i] = (buf + n < table.length ())? table[buf + n]
	    : table[buf + n - table.length ()];
	}
    }
  return ans;
}

int
main ()
{
  string str;
  while (getline (cin, str))
    {
      string after;
      for (int i = 0; i <= 25; i++)
	{
	  after = caesar (str, i);
	  if (after.find ("the") != string::npos)
	    break;
	  if (after.find ("this") != string::npos)
	    break;
	  if (after.find ("that") != string::npos)
	    break;
	}
      cout << after << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <deque>
#include <list>
#include <string>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <stdio.h>

using namespace std;

int pat[3][3];
int len[3];
int chr[3];
int zure;
int size;
bool atteru[3];
char text[100];

int main() {
	//cin >> text;
	gets(text);
	//int size = text.size();
	int pt = 0;
	size = 100;

	pat[0][0] = 't' - 'h';
	pat[0][1] = 'h' - 'e';
	pat[1][0] = 't' - 'h';
	pat[1][1] = 'h' - 'i';
	pat[1][2] = 'i' - 's';
	pat[2][0] = 't' - 'h';
	pat[2][1] = 'h' - 'a';
	pat[2][2] = 'a' - 't';
	chr[0] = 'e';
	chr[1] = 's';
	chr[2] = 't';
	len[0] = 3;
	len[1] = 4;
	len[2] = 4;

	for (int i = 0; i < 3; i++) {
		for (int j = 0; j < 3; j++) {
			if (pat[i][j] < 0) pat[i][j] += 26;
		}
	}

	zure = -1;

	int cnt = 0;
	atteru[0] = true;
	atteru[1] = true;
	atteru[2] = true;
	for (int i = 0; i < size-1 && zure == -1; i++) {
		if (text[i+1] == ' ' || cnt > 3) continue;
		if (text[i] == ' ') {
			cnt = 0;
			atteru[0] = true;
			atteru[1] = true;
			atteru[2] = true;
			//cout << "yarinaoshi!" << endl;
			continue;
		}
		int dist = text[i] - text[i+1];
		if (dist < 0) dist += 26;
		for (int j = 0; j <= 2; j++) {
			if (!atteru[j]) continue;
			if (cnt >= len[j]-1) continue;
			if (dist != pat[j][cnt]) {
				atteru[j] = false;
				//cout << j << " ha tigau!" << endl;
				continue;
			} else if (cnt == len[j]-2) {
				//cout << j << " ha atteta!" << endl;
				zure = text[i+1] - chr[j];
				if (zure < 0) zure += 26;
				//cout << "zure = " << zure << endl;
			}
		}
		cnt++;
	}

	for (int i = 0; i < size; i++) {
		if (text[i] == '.') break;
		if (text[i] == ' ') continue;
		text[i] = text[i] - zure;
		if (text[i] < 'a') text[i] += 26;
	}

	cout << text << endl;

	return 0;
}

/*@@@@@@@@@@@@@@@@@@@@@@@@@*/
/*@                       @*/
/*@ debug output erased ? @*/
/*@                       @*/
/*@@@@@@@@@@@@@@@@@@@@@@@@@*/

C++: #include<iostream>
#include<string>
using namespace std;
main(){
	string str;
	int tmp,b;
	while(getline(cin,str)){
		tmp='t'-str[0];
		for(int i=0;i<str.size();++i){
			if(str[i]>='a' && str[i]<='z'){
				if(str[i]>='m')str[i]-=26;
				str[i]+=tmp;
				if(str[i]<'a')str[i]+=26;
				else if(str[i]>'z')str[i]-=26;
			}
		}
		string str2="";
		for(int i=0;i<=4;++i){
			if(str[i]>='a' && str[i]<='z')str2+=str[i];
			else break;
		}
		if(str2=="this" || str2=="the" || str2=="that")cout<<str<<endl;
	}
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
int main()
{
	string s;
	while(1)
	{
		getline(cin,s);
		if(cin.eof())break;
		int slidenum=0,len = s.size();
		string ss = s;
		rep(i,26)
		{
			rep(j,len)
			{
				if(s[j]>='a' && s[j]<='z'){ss[j] = ((s[j] - 'a' + i) % 26) +'a';}
			}
			int index[3];
			index[0] = ss.find("this");
			index[1] = ss.find("that");
			index[2] = ss.find("the");
			
			if(index[0]!=string::npos || index[1]!=string::npos || index[2]!=string::npos)break;
		}
		cout << ss<<endl;
	}

	return 0;
}

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

using namespace std;

int main()
{
	string s;
	int pl;
	while(getline(cin,s))
	{
		if(s=="\n" && s=="EOF") 
			break;

		pl = 0;

		for(int i =-30;i<30;i++)
		{
			for(int j = 0; j < s.size()-3; j++)
			{
				if(s[j]+i=='t' &&s[j+1]+i == 'h' && s[j+2]+i == 'e')
				{
					pl = i;
					break;
				}

				if(j==s.size()-1) 
					break;

				if(s[j]+i=='t' &&s[j+1]+i == 'h' && s[j+2]+i == 'a' && s[j+3]+i=='t')
				{
					pl = i;
					break;
				}

				if(s[j]+i=='t' &&s[j+1]+i == 'h' && s[j+2]+i == 'i' && s[j+3]+i=='s')
				{
					pl = i;
					break;
				}
			}

			if(pl!=0) 
				break;
		}

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

		cout<<s<<endl;
	}
}