Go: package main

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

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 len(infos) == 0 {
			break
		}
		// 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 <stdio.h>
#include <string.h>

struct words {
	char str[80] ;
} w[80] ;

int p ;
int key ;
char c ;

bool isalpha ( char s ) ;

int main ( )
{
	p = 0 ;
	key = 9999 ;
	while ( true ) {
		int t = scanf ( "%s" , w[p].str ) ;
		if ( t == EOF ) {
			break ;
		}
		c = getchar ( ) ;
		if ( strlen ( w[p].str ) == 4 && key == 9999 ) {
			if ( w[p].str[0] - w[p].str[1] == 't' - 'h' && w[p].str[1] - w[p].str[2] == 'h' - 'i' && w[p].str[2] - w[p].str[3] == 'i' - 's' ) {
				key = 't' - w[p].str[0] ;
			}
			else if ( w[p].str[0] - w[p].str[1] == 't' - 'h' && w[p].str[1] - w[p].str[2] == 'h' - 'a' && w[p].str[2] - w[p].str[3] == 'a' - 't' ) {
				key = 't' - w[p].str[0] ;
			}
		}
		else if ( strlen ( w[p].str ) == 3 && key == 9999 ) {
			if ( w[p].str[0] - w[p].str[1] == 't' - 'h' && w[p].str[1] - w[p].str[2] == 'h' - 'e' ) {
				key = 't' - w[p].str[0] ;
			}
		}
		p++ ;
		if ( c == '\n' ) {
			for ( int i = 0 ; i < p ; i++ ) {
				for ( int j = 0 ; w[i].str[j] ; j++ ) {
					if ( isalpha ( w[i].str[j] ) ) {
						w[i].str[j] += key ;
						if ( w[i].str[j] - 'a' > 26 ) {
							w[i].str[j] -= 26 ;
						}
						else if ( w[i].str[j] - 'a' < 0 ) {
							w[i].str[j] += 26 ;
						}
					}
				}
				if ( i != 0 ) {
					printf ( " " ) ;
				}
				printf ( "%s" , w[i].str ) ;
			}
			printf ( "\n" ) ;
			p = 0 ;
			key = 9999 ;
		}
	}
	return 0 ;
}

bool isalpha ( char s )
{
	return ( s >= 'a' && s <= 'z' ) ;
}

C++: #include <iostream>
using namespace std;

bool isSmallAlphabet(char& ch) {
  /* a ~ z(ascii) : 97 ~ 122 */
  if('a' <= ch && ch <= 'z') return true;
  else return false;
}

bool isHit(string& str) {
  if(str.find("the") != str.npos) return true;
  else if(str.find("this") != str.npos) return true;
  else if(str.find("that") != str.npos) return true;
  else return false;
}

/* ????????¶??????????§£??? */
void CaesarCipher(string& _str) {
  
  /* parameter??????????????¢??????????????????????????????????????? */
  for(int parameter = 0; parameter < 26; ++parameter) {
    string str = _str;
    for(int i = 0; i < (int)str.length(); ++i) {
      
      /* ?°?????????¢??????????????????????????? */
      if(isSmallAlphabet(str[i])) {
        str[i] += parameter;
        /* ???????????????????°?????????§???????????£??????*/
        if(!isSmallAlphabet(str[i])) {
          str[i] -= 26;
        }
      }

    }

    /* Find "the" or "this" or "that" */
    if(isHit(str)) {
      cout << str << endl;
    }
  }
}

int main() {
  string str;
  while(getline(cin, str)) {
    CaesarCipher(str);
  }
  return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#define GETSTR(p)       do{ fgets((p), sizeof(p), stdin); } while(0)
#define CHOMP(p)        do{ char *_q = (p) + strlen(p)-1; if(*_q == '\n') *_q = 0;            } while(0)

int main(void){
    char buf[100];
    GETSTR(buf);
    CHOMP(buf);
    int len = strlen(buf);

    const int nn = 'z' - 'a' + 1;

    while(1){
        for(int i = 0; i < len; i++){
            if(isalpha(buf[i])){
                buf[i] = 'a' + (buf[i] - 'a' + nn + 1) % nn;
            }
        }
        char buf2[100];
        sprintf(buf2, " %s ", buf);
        int l = strlen(buf2);
        for(int i = 0; i < l; i++){
            if(! isalpha(buf2[i])) buf2[i] = ' ';
        }
        if(strstr(buf2, " the ") != NULL) break;
        if(strstr(buf2, " this ") != NULL) break;
        if(strstr(buf2, " that ") != NULL) break;
    }
    puts(buf);

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <vector>
#include <string>
#include <ctype.h>
#include <algorithm>
using namespace std;

#define loop(i,a,b) for(int i=(a); i<(int)(b); i++)
#define rep(i,b) loop(i,0,b)
#define all(c) (c).begin(), (c).end()
 
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;

int main() {
  string s; getline(cin, s);
  int slide = 0;
  rep(i, s.size()-4) {
    if(islower(s[i]) == 0) continue;
    rep(j, 26) {
      string sub;
      rep(k, 4) sub += (s[i+k]-'a'+j+26)%26 + 'a';
      if(sub.substr(0,3) == "the") slide = j;
      else if(sub == "this" || sub == "that") slide = j;
    }
    if(slide != 0) break;
  }
  rep(i, s.size()) {
    if(islower(s[i]) != 0)printf("%c", (s[i]-'a'+slide+26)%26 + 'a');
    else cout << s[i];
  }
  cout << endl;
}

C++: #include<iostream>
#include<cstring>
using namespace std;
int main(){
  char str;
  while(1){
    str = getchar();
    if(str=='.'){
      cout<<str;
      break;
    }
    if(str!=' '){
      str=str-4;
      cout<<str;
    }else{
      cout<<" ";
    }
  }
  cout<<endl;
}

C++: #include <bits/stdc++.h>
 
using namespace std;
 
#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define repr(i, j) for(int i = j; i >= 0; --i)
#define INF (1 << 30)
#define MOD 1e9 + 7
 
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
 
int main() {
    string s;
    bool flag = false;
    int key = 1;
    while(getline(cin, s)){
    	while(s.find("this") == string::nops && s.find("that") == string::nops && s.find("the") == string::nops) {
	    	rep(i, s.size()) {
	            if(97 <= s[i] && s[i] <= 122) {
	                int number = (s[i] - 'a' + key) % 26;
	                s[i] = 'a' + number;
	            }
	        }
	    }
	    cout << s << endl;
    }
    return 0;
}

C++: #include <stdio.h>

int main(void)
{
	char str[100];
	int num;
	int i;
	
	while (fgets(str, 100, stdin) != NULL){
		num = 't' - str[0];
		i = 0;
		while (str[i] != '\0'){
			if ((str[i] >= 'A' && str[i] <= 'Z') || (str[i] >= 'a' && str[i] <= 'z')){
				str[i] += num;
			}
			i++;
		}
		printf("%s", str);
	}
	
	printf("\n");
	
	return (0);
}