Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

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 scanner.Scan() {
		infos := strings.Split(scanner.Text(), " ")
		plain := make([]string, len(infos))
		// 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>
#define REP(i,n) for(int i=0;i<n;i++)
#define LOOP(i,x,n) for(int i=x;i<n;i++)
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define MP make_pair
#define FR first
#define SC second
#define int long long
using namespace std;
const int MOD=1000000007;
const int INF=9000000009;

signed main(){
  string s;
  while(getline(cin,s)){
    vector<int> spe;
    REP(i,s.size())if(s[i]==' ')spe.PB(i);
    int f=0;
    LOOP(i,1,27){
      string t;
      REP(j,s.size()-1){
        if(s[j]==' ')continue;
        if((s[j]+i)<=122){
          t+=(s[j]+i);
        }else{
          t+=((s[j]+i)-26);
        }
      }
      REP(j,t.size()){
        if(t.substr(j,3)=="the"||t.substr(j,4)=="that"||t.substr(j,4)=="this"){
          int p=0;
          REP(k,t.size()){
            if(k==spe[p]-p-1){
              cout<<t[k]<<' ';
              p++;
            }else{
              cout<<t[k];
            }
          }
          cout<<'.'<<endl;
          f=1;
          break;
        }
      }
      if(f)break;
    }
  }
  return 0;
}

C++: #include <cmath>
#include <iostream>
#include <string>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <sstream>

using namespace std;

string decode(string inp,int n){
    for(int i=0;i<inp.length();i++){
        if('a'<=inp[i]&&inp[i]<='z'){
            
            inp[i]=inp[i]-n;
            if(inp[i]<'a') inp[i]+=('z'-'b');
        }
    }
    return inp;
}
bool check(string inp){
    string word;
    stringstream ss(inp);
    while(getline(ss,word,' ')){
        if(word=="the"||word=="this"||word=="that"||word=="the."||word=="this."||word=="that.")
            return true;
    }
    return false;
}
int main(){
    string input,decoded;
    while(getline(cin,input)){
        for(int i=0;i<26;i++){
            decoded=decode(input,i);
            if(check(decoded)){
                break;
            }
        }
        cout << decoded << endl;
    }
    return 0;
}

C++: 
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <stack>
#include <cctype>
#include <complex>
#include <vector>
#include <algorithm>

using namespace std;


bool solve(){
	
	string s;
	while(getline(cin,s)){
		string str[26];
		int num;
		for(int i=0;i<26;i++){
			str[i] = s;
			for(int j=0;j<str[i].size();j++){
				for(int k=0;k<i;k++){
					if(str[i][j]=='.' || str[i][j]==' '){
						continue;
					}
					if(str[i][j] == 'a'){
						str[i][j] = 'z';
						continue;
					}
					str[i][j]--; 
				}
			}
			
			for(int j=0;j<str[i].size();j++){
				string str_temp, str_temp2;	
				if(j+3 <= str[i].size()){
					str_temp  = str[i].substr(j,3);
				}
				if(j+4 <= str[i].size()){
					str_temp2 = str[i].substr(j,4);
				}
				if(str_temp=="the" || str_temp2=="this" || str_temp2=="that"){
					num = i;
				}
			}
		}
		
		
		cout<< str[num]<< endl;
	}		
	
	return true;
}

int main(){
	cout.setf(ios::fixed);
	cout.precision(10);
	solve();

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#include<cstdio>
#include<cstring>
using namespace std;
int main(){
  string str;
  char s[256];
  int w = 0;
  while(scanf(" %c",&s[0]) != EOF){
    do {
      w++;
      scanf("%c",&s[w]);
    }while(s[w] != '\n');
    while(1){
      s[w+1] = '\0';
    
      for(int i=0;i<w;i++){
	if(s[i] != ' ' && s[i] != '.'){
	  s[i]++;
	  if(s[i]>'z')s[i] = s[i] - 'z' + 'a' - 1;
	}
      }
      if(strstr(s,"the") != NULL)break;
      if(strstr(s,"that") != NULL)break;
      if(strstr(s,"this") != NULL)break;
    }
    printf("%s",s);
    memset( s , 0 , sizeof(s) );
  }
}

C++: #include <iostream>
#include <cmath>
#include <cstdio>
#include <vector>

using namespace std;
string s;
char decrypt[100];
int key,i;

int main(){
    while(getline(cin,s)){
        const char *encrypt = s.c_str();
        while(encrypt[i] != '\0'){
            if(i == 0 && encrypt[i] - encrypt[i+1] == 12){
                key = 't' - encrypt[i];
                break;
            }
            else if(i >= 1 && encrypt[i-1] == ' ' && encrypt[i] - encrypt[i+1] == 12){
                key = 't' - encrypt[i];
                break;
            }
            i++;
        }

        i = 0;
        while(encrypt[i] != '\0'){
            if(encrypt[i] <= 'z' && encrypt[i] >= 'a'){
                decrypt[i] = (encrypt[i] - 'a' + key + 26) % 26 + 'a';
            }
            else{
                decrypt[i] = encrypt[i];
            }
            i++;
        }
        while(i <= 99){
            decrypt[i] = '\0';
            i++;
        }
        printf("%s\n", decrypt);
    }
    return 0;
}

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

int main() {
  char buf[82];
  char *p;
  int l;
  string str;

  while (cin.getline(buf, 82)) {
    l = strlen(buf);

    for (int i=0; i<26; i++) {
      for (int j=0; j<l; j++) {
        if (buf[j]>='a' && buf[j]<='z') {
          buf[j] = (buf[j]-'a'+1)%26 + 'a';
        }
      }
      str.assign(buf);
      if (str.find("the")!=string::npos ||
          str.find("this")!=string::npos ||
          str.find("that")!=string::npos) {
        break;
      }
    }

    cout << str << endl;
  }
  return 0;
}

C++: #include <stdio.h>
#include <string.h>

int main(void)
{
	int i;
	int len;
	int f;
	int n;
	char str[128];
	
	while (fgets(str, 100, stdin) != NULL){
		f = 0;
		n = 0;
		while (1){
			len = strlen(str);
			for (i = 0; i < len; i++){
				if (strncmp(&str[i], "the", 3) == 0){
					f = 1;
				}
				if (strncmp(&str[i], "this", 4) == 0){
					f = 1;
				}
				if (strncmp(&str[i], "that", 4) == 0){
					f = 1;
				}
			}
			if (f == 1){
				break;
			}
			for (i = 0; i < len; i++){
				if (str[i] >= 'a' && str[i] < 'z'){
					str[i]++;
				}
				else if (str[i] == 'z'){
					str[i] = 'a';
				}
			}
			n++;
		}
		printf("%s", str);
	}
	return (0);
}