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 <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define INF INT_MAX/3
#define ALL(a) (a).begin(),(a).end()
#define CLR(a) memset(a,0,sizeof(a))

typedef long long int ll;

using namespace std;

int main(){

    string s[] = {"the","this","that"};
    string in;
    while(true){
	getline(cin,in);
	if(cin.eof()) break;
	bool f = false;
	int d = 1;
	REP(i,30){

	    f = true;
	    REP(i,in.size()){
		if(in[i] == '.' || in[i] == ' ') continue;
		in[i]= (char)( 'a' + ( (int)(in[i] - 'a') + d) % 28);
	    }
	    vector<bool> flgs(3,false);
	    for(int i=0;i<in.size();i++){
		REP(j,3){
		    if(in.substr(i,s[j].size()) == s[j]) flgs[j] = true;
		}
	    }
	    if(flgs[0] && (flgs[1] || flgs[2])) break;
	}
	cout << in << endl;
    }

    return 0;
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<list>
#include<stack>
#include<queue>
#include<iomanip>
#include<functional>
using namespace std;
typedef long long llong;
int main() {
	int p, q, r;
	string x = "this the that";
	//cout << x.find("the") << endl << x.find("that") << endl << x.find("this") << endl;
	string a = "abcde";
	//cout << (int)a.find("the") << endl << (int)a.find("that") << endl << (int)a.find("this") << endl;
	string s;
	while (getline(cin, s)) {
		//cout << (int)s.find("the") << endl << (int)s.find("that") << endl << (int)s.find("this") << endl;
		for (int j = 0;; j++) {
			p = (int)s.find("the");
			q = (int)s.find("that");
			r = (int)s.find("this");
			//cout << p << q << r << endl;
			if (p >= 0 || q >= 0 || r >= 0) {
				cout << s << endl;
				break;
			}
			for (int i = 0; i < s.size(); i++) {
				if (isalpha(s[i])) {
					if (s[i] == 'z')s[i] = 'a';
					else s[i]++;

				}
			}
		}
	}
	return 0;
}

C++: #include<bits/stdc++.h>
#include<sstream>
using namespace std;

typedef long long int ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pair<int, int> > vii;
#define rrep(i, m, n) for(int (i)=(m); (i)<(n);  (i)++)
#define erep(i, m, n) for(int (i)=(m); (i)<=(n); (i)++)
#define  rep(i, n)    for(int (i)=0; (i)<(n);  (i)++)
#define rrev(i, m, n) for(int (i)=(n)-1; (i)>=(m); (i)--)
#define erev(i, m, n) for(int (i)=(n); (i)>=(m); (i)--)
#define  rev(i, n)    for(int (i)=(n)-1; (i)>=0; (i)--)
#define vrep(i, c)    for(__typeof((c).begin())i=(c).begin(); i!=(c).end(); i++)
#define  ALL(v)       (v).begin(), (v).end()
#define mp            make_pair
#define pb            push_back
template<class T, class S> inline bool minup(T& m, S x){ return m>(T)x ? (m=(T)x, true) : false; }
template<class T, class S> inline bool maxup(T& m, S x){ return m<(T)x ? (m=(T)x, true) : false; }

const int    INF = 1000000000;
const ll     MOD = 1000000007LL;
const double EPS = 1E-12;

template<typename T> ostream& operator << (ostream& r, const vector<T> t){vrep(v,t)r<<*v<<(v+1==t.end()?"":" ");return r;}
template<typename T> ostream& operator << (ostream& r, const pair<vector<T>, int> p){int n=p.second;minup(n,p.first.size());rep(i,n-1)r<<p.first[i]<<' ';r<<p.first[n-1];return r;}
template<typename T> ostream& operator << (ostream& r, const pair<T*, int> p){int n=p.second-1;rep(i,n)r<<p.first[i]<<' ';return r<<p.first[n];}
template<typename T, size_t S> ostream& operator << (ostream& r, const T (&a)[S]){rep(i,S-1)r<<a[i]<<' ';return r<<a[S-1];}

string str;

int main()
{
  while(getline(cin, str)){
    vector<string> s;
    istringstream stream(str);
    while(getline(stream, str, ' ')) s.pb(str);
    bool ok = false;
    rep(k, 26){
      vrep(v, s) rep(i, v->size()) if((*v)[i] >= 'a' && (*v)[i] <= 'z') (*v)[i] = 'a' + ((*v)[i] + 1) % 26;
      vrep(v, s) if(*v == "the" || *v == "this" || *v == "that") ok = true;
      if(ok){
        cout << s << endl;
        break;
      }
    }
  }

 return 0;
}

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

int caesar[26][255], x, enkrip[100];
int thiss[] = {'t', 'h', 'i', 's'}, the[] = {'t', 'h', 'e'}, that[] = {'t', 'h', 'a', 't'};
string s;
int main() {
	for(int i = 0; i <= 25; i++) {
		for(char j = 'a'; j <= 'z'; j++) {
			if(j + i > 'z') x = j + i - 26; else x = j + i;
			caesar[i][x] = j;
		}
	}
	while(getline(cin, s)) {
	for(int k = 0; k <= 25; k++) {
		int l = 0, z = 0, zz = 0;
		for(int i = 0, j = s.size(); i != j; i++) {
			if(s[i] <= 'z' && s[i] >= 'a') {
				enkrip[i] = caesar[k][s[i]];
				if(enkrip[i] == thiss[l]) l++;
				if(enkrip[i] == the[z]) z++;
				if(enkrip[i] == that[zz]) zz++;
			} else {enkrip[i] = s[i]; if(l != 4) l = 0; if(z != 3) z = 0;if(zz != 4) zz = 0; }
		}
		if(l == 4 || z == 3 || zz == 4) {
			for(int i = 0, j = s.size(); i != j; i++) {
				printf("%c", enkrip[i]);
			}
			printf("\n");
			break;
		}
	}}
	return 0;
}

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

using namespace std;

int main() { 
  string input_str;

  getline(cin, input_str);

  while (1) {
    for (int str_i = 0; str_i < input_str.size(); str_i++)
      if (!isspace(input_str[str_i]) && input_str[str_i] != '.')
        input_str[str_i]--;
    if (input_str.find("the") != string::npos ||
        input_str.find("this") != string::npos ||
        input_str.find("that") != string::npos)
      break;
  }

  cout << input_str << endl;

  return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;
void nstr(string st,int n){
  for(int k =0;k<st.length();k++){
    if(st[k] != ' ' && st[k] != '.'){
      if(st[k]+n > 122){
	st[k] = st[k]+n - 26;
      } else {st[k] = st[k] + n;}
    }
  }
  if(st.find("the") != string::npos ||st.find("this") != string::npos ||st.find("that") != string::npos){
      cout << st << endl;
    }
}

int main(){
  int i = 0,count=0;
  string str;
  string tmp;
  while(getline(cin,str)){
     for(int p=0;p<=25;p++){
       nstr(str,p);
     }
  }
}

C++: #include<bits//stdc++.h>
using namespace std;

int main(){
	string sa;
	while(getline(cin,sa)){
		int a=sa.size();
		while(1){
		for(int i=0;i<a;i++){
			if('a'<=sa[i]&&sa[i]<='z'){sa[i]+=1;}
				if(sa[i]>'z'){sa[i]-=26;}
			}
			if(sa.find("this"||"that"||"the")!=string::npos){
				break;
				}
		}
		cout<<sa<<endl;
		}
		return 0;
	}