Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		var result string
		line := scanner.Text()
		key := make(map[string]string)

		var i int32
		for ; i < 52; i++ {
			makeKey(key, i)
			result = decode(key, line)

			if strings.Contains(result, "the") {
				break
			} else if strings.Contains(result, "this") {
				break
			} else if strings.Contains(result, "that") {
				break
			}
		}

		fmt.Println(result)
	}
}

func makeKey(key map[string]string, shift int32) {
	for i := 'a'; i <= 'z'; i++ {
		cipher := (i + shift)
		if cipher > 'z' {
			cipher = cipher%'z' + 'a' - 1
		} else if cipher < 'a' {
			cipher = cipher + ('z' - 'a') + 1
		}
		key[string(i)] = string(cipher)
	}
}

func decode(key map[string]string, cipher string) string {
	var result string
	for _, v := range cipher {
		if key[string(v)] != "" {
			result += key[string(v)]
		} else {
			result += string(v)
		}
	}
	return result
}

C++: #include <string>
#include <vector>
#include <algorithm>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <map>
#define INF 100000000

using namespace std;
typedef long long ll;

string change(string s){
    int len=s.size();
    for(int i=0;i<len;i++){
        if(s[i]=='a')s[i]='z';
        if('b'<=s[i] && s[i]<='z')s[i]--;
    }
    return s;
}

bool check(string s){
    int len=s.size();
    string tan="";
    for(int i=0;i<len;i++){
        if('a'<=s[i] && s[i]<='z'){
            tan+=s[i];
        }
        if((s[i]<'a' && 'z'<s[i]) || i==len-1){
            if(tan=="the" || tan=="this" || tan=="that" )return true;
            tan="";
        }
    }
    return false;
}


int main(){
    string s;
    while(getline(cin,s)){
        for(int i=0;i<26;i++){
            s=change(s);
            if(check(s)){cout<<s<<endl;break;}
        }
    }
    return 0;
}

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

bool isSmallAlpha(char c){
	return 'a' <= c && c <= 'z';
}

void encode(std::string& str, int s){
	for(int i=0; i < str.size(); i++){
		if(isSmallAlpha(str[i])){
			str[i] = (str[i] - 'a' + s) % 26 + 'a';
		}
	}
}

int main() {
	std::string s;
	while(std::getline(std::cin, s)){
		for(int i = 0; i < 26; i++){
			encode(s, 1);
			if(s.find("the") != std::string::npos ||
			   s.find("that") != std::string::npos ||
			   s.find("this") != std::string::npos){
				std::cout << s << std::endl;   	
			}
		}
	}
	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>

using namespace std;
typedef long long ll;

int main(){
    int in;
    char S[1000];
    
    for(int i=0;;i++){
        
        in = getchar();
        
        if(in==EOF){
            S[i]='\0';
            break;
        }else{
            S[i]=(char)in;
        }
    }
    
    for(int k=0;k<27;k++){
        
        bool f = false;
        
        for(int i=0;;i++){
            if('a'<=S[i] && S[i]<='y'){
                S[i]++;
            }else if(S[i]=='z'){
                S[i]='a';
            }
            
            if(i>=3 && !('a'<=S[i] && S[i]<='z')){
                if(S[i-3]=='t' && S[i-2]=='h' && S[i-1]=='e')
                    f=true;
            }
            if(i>=4 && !('a'<=S[i] && S[i]<='z')){
                if(S[i-4]=='t' && S[i-3]=='h')
                    if((S[i-2]=='i' && S[i-1]=='s') || (S[i-2]=='h' && S[i-1]=='t'))
                        f=true;
            }
            
            if(S[i]=='\0') break;
        }
        
        if(f) break;
    }
    
    for(int i=0;S[i]!='\0';i++)
        printf("%c",S[i]);
    
    return 0;
}

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

using namespace std;

int main(){

    const string keyword[] = {"the", "this", "that"};
    string str = "";

    while(getline(cin, str)){
        int len = str.length();
        vector <bool> match(3, false);

        int i,j;

        for(j=0; j<26; j++){
            string current = str;
            for(i=0; i<len; i++){
                if(isalpha(str[i])){
                        current[i] = (str[i] - 'a' + j) % 26 + 'a';
                }
            }

            for(i=0; i<3; i++){
                if(current.find(keyword[i]) != string::npos){
                    match[i] = true;
                }
            }

            if((int)count(match.begin(), match.end(), true) > 0){
                cout << current << endl;
                break;
            }
        }
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define NCLR(a) memset((a), -1 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
typedef complex<double> P;
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 1000000007;
static const int INF = 1 << 30;
static const LL LL_INF = 1152921504606846976;
static const int dx[] = { -1, 0, 1, 0, 1, -1, 1, -1 };
static const int dy[] = { 0, -1, 0, 1, 1, 1, -1, -1 };

string str;

int main() {
	getline( cin, str );
	for ( ;; ) {
		for ( int j = 0; j < str.size(); j++ ) {
			if ( str[ j ] >= 'a' && str[ j ] <= 'z' ) {
				str[ j ] = ( ( str[ j ] - 'a' + 25 ) % 26 ) + 'a';
			}
		}
		bool is_can = false;
		for ( int j = 0; j < str.size() - 2; j++ ) {
			if ( str.substr( j, 3 ) == "the" ) {
				is_can = true;
				break;
			}
		}
		for ( int j = 0; j < str.size() - 3; j++ ) {
			if ( str.substr( j, 4 ) == "that" || str.substr( j, 4 ) == "this" ) {
				is_can = true;
				break;
			}
		}
		if ( is_can ) {
			break;
		}

	}
	printf( "%s\n", str.c_str() );
	return 0;
}

C++: #include <iostream>
#include <cstring>
#include <stdio.h>

int find(const std::string &str){
	return (str.find("this",0)!=std::string::npos) + (str.find("that",0)!=std::string::npos) + (str.find("the",0)!=std::string::npos);
}

std::string rot(const std::string &prm, int n)
{
	std::string str=prm;

	for(int i=0; i < str.size(); i++){
		if(('a'<=str[i]) && (str[i]<='z'))
			str[i] = (str[i]+n > 'z')?(str[i]+n-'z'+'a'-1):(str[i]+n);
	}
return str;
}
	
int main(void)
{
	char s[81]="";
	while(std::cin.getline(s,sizeof(s)))
	{
		std::string in=s;
		for(int i=0;i < ('z'-'a');i++)
		{
			if(find(rot(in, i))){
				std::cout << rot(in, i) << std::endl;
				break;
			}
		}
	}
	return 0;
}