Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func cipher(text string, direction int, int_shift int) string {
	shift, offset := rune(int_shift), rune(26)
	runes := []rune(text)
	for index, char := range runes {
		switch direction {
		case 1:
			if char >= 'a' && char <= 'z'-shift || char >= 'A' && char <= 'Z'-shift {
				char = char + shift
			} else if char > 'z'-shift && char <= 'z' || char > 'Z'-shift && char <= 'Z' {
				char = char + shift - offset
			}
		case -1:
			if char >= 'a'+shift && char <= 'z' || char >= 'A'+shift && char <= 'Z' {
				char = char - shift
			} else if char >= 'a' && char < 'a'+shift || char >= 'A' && char < 'A'+shift {
				char = char - shift + offset
			}
		}
		runes[index] = char
	}
	return string(runes)
}

func main() {
	for {
		infos := strings.Split(nextString(), " ")
		plain := make([]string, len(infos))
		if reflect.DeepEqual(infos, []string{}) {
			break
		}
		fmt.Println(infos)
		Decryption:
			for i := 0; i < 26; i++ {
				for j := range infos {
					plain[j] = cipher(infos[j], 1, i)
				}
				for j := range plain {
					if plain[j] == "this" || plain[j] == "that" || plain[j] == "the" {
						break Decryption
					}
				}
			}
			fmt.Println(strings.Join(plain, " "))
	}
}

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;
map<char, char> change;

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

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

C++: #include<stdio.h>
#include<string.h>
int main(void){
    int i,j,k;
    char input[100],cpyinput[100],key[3][5]={"the","this","that"};
    while(gets(input)!=NULL){
        for(i=0;i<26;i++){
            for(j=0;j<strlen(input);j++){
                if('a'<=input[j] && input[j]<='z'){
                    input[j]+=1;
                    if(input[j]>'z')
                        input[j]-=26;
                }
                //printf("%c",input[j]);
            }
            //puts("");
            //printf("%s\n",input);
            //puts("test");
            for(j=0;j<3;j++){
                if(strstr(input,key[j])!=NULL){
                    //printf("test");
                    goto next;
                }
            }
        }
        next:
        printf("%s\n",input);
    }
    return 0;
}

C++: #include<iostream>
using namespace std;
bool isAlpha(char ch){
  return ('a'<=ch&&ch<='z');
}
string change(string str){
  for(int i=0;i<(int)str.size();i++){
    if(isAlpha(str[i])){
      if(str[i]=='z')str[i]='a';
      else str[i]++;
    }
  }
  return str;
}
int main(){
  int i,j;
  string str;
  
  getline(cin,str);
  for(i=0;i<26;i++){
    str=change(str);
    for(j=0;j+3<(int)str.size();j++)
      if(str.substr(j,3)=="the")break;
    for(j=0;j+4<(int)str.size();j++)
      if(str.substr(j,4)=="this")break;
    for(j=0;j+4<(int)str.size();j++)
      if(str.substr(j,4)=="that")break;
  }
  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;

    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;
}