Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

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

func incrementByte(b byte) byte {
	if b >= 97 && b < 122 {
		return b + 1
	} else if b == 122 {
		return 97
	}
	return b
}

func main() {
	scanner.Split(bufio.ScanLines)

	for {
		line := nextString()
		if len(line) == 0 {
			break
		}
		for i := 0; i <= 26; i++ {
			decoded := []byte{}
			for j := 0; j < len(line); j++ {
				decoded = append(decoded, incrementByte(line[j]))
			}
			line = string(decoded)
			if strings.Contains(line, "the") || strings.Contains(line, "this") || strings.Contains(line, "that") {
				fmt.Println(line)
				break
			}
		}
	}
}

C++: #include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
const ld eps = 1e-9;

//// < "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\a.txt" > "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\b.txt"


int main() {
	string st;
	vector<string>ths{ " the "," this "," that " };
	while (getline(cin, st)) {
		st.push_back(' ');
		st.insert(st.begin(), ' ');
		for (int i = 1; i < 26; ++i) {
			string nextst(st);
			for (auto&c : nextst) {
				int n = c - 'a';
				if (n < 0 || n >= 26)continue;
				n += i;
				n %= 26;
				c = 'a' + n;
			}
			bool ok = false;
			for (auto th : ths) {
				if (nextst.find(th) != -1)ok = true;
			}
			if (ok) {
				cout << nextst.substr(1,nextst.size()-2) << endl;
				break;
			}
		}
	}
	return 0;
}

C++: // clang-format off

#include <bits/stdc++.h>

#define int long long int
#define main signed main()
#define bye return 0
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define each(p, v) for (auto p = (v).begin(); p != (v).end(); p++)
#define all(v) (v).begin(), (v).end()
#define prec(n) fixed << setprecision(n)
#define dump(x) cerr << "(L" << __LINE__ << ") " << #x << " = " << (x) << endl
#define clr(x, a) memset(x, a, sizeof(x))

#define stlice(from, to) substr(from, (to) - (from) + 1)
#define odd(n) ((n) % 2)
#define even(n) (!odd(n))

#define INF 1000000000
#define INFLL 1000000000000000000LL
#define MOD 1000000007
#define PI acos(-1)

#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define vi vector<int>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define pii pair<int, int>

using namespace std;

// clang-format on

string f(string s) {
  rep(i, s.size()) {
    if ('a' <= s[i] && s[i] <= 'z') {
      s[i] = (s[i] - 'a' + 1) % ('z' - 'a') + 'a';
    }
  }
  return s;
}

main {
  string s;
  while (getline(cin, s)) {
    vs w;
    stringstream ss;
    ss << s;
    string x;
    while (ss >> x) {
      w.pb(x);
    }
    if (w.size() == 0) {
      continue;
    }
    for (bool b = false; !b;) {
      rep(i, w.size()) {
        string d = f(w[i]);
        b |= d.substr(0, 3) == "the" || d.substr(0, 4) == "this" ||
             d.substr(0, 4) == "that";
        w[i] = d;
      }
    }
    cout << w[0];
    loop(i, 1, w.size()) cout << ' ' << w[i];
    cout << endl;
  }
}

C++: #include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<algorithm>
#include<set>
#include<queue>
#include<string>
#include<vector>
#include<map>
#include<stack>
#include<list>
using namespace std;
#define inf 0x3f3f3f3f

char d[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

int main(){
	char s[110];
	char c;
	int i=0;
	gets(s);
	int l = strlen(s),j,k,m,t;
	for(i=0;i<=26;i++){
		char t[110]={'a'};
		for(j=0;j<l;j++){
			if(s[j]>='a'&&s[j]<='z'){
				t[j] = d[(s[j]-'a'+i)%26];
			}
			else t[j] =s[j];
		}
		int a=0,b=0,c=0;
		for(j=0;j<l-2;j++){
			if(t[j]=='t'&&t[j+1]=='h'){
				if(t[j+2]=='e'&&!(t[j+3]>='a' && t[j+3]<='z')){
					a++;
				}
				if(t[j+2]=='i'&&t[j+3]=='s'&&!(t[j+4]>='a'&&t[j+4]<='z')){
					b++;
				}
				if(t[j+2]=='a'&&t[j+3]=='t'&&!(t[j+4]>='a'&&t[j+4]<='z')){
					c++;
				}
			}
		}
		if(a&&b&&c)break;
	}
	for(j=0;j<l;j++){
		if(s[j]>='a'&&s[j]<='z'){
			printf("%c",d[(s[j]-'a'+i)%26]);
		}
		else printf("%c",s[j]);
	}
	puts("");
	return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<algorithm>
#include<set>
#include<queue>
#include<string>
#include<vector>
#include<map>
#include<stack>
#include<list>
using namespace std;
#define inf 0x3f3f3f3f

char d[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

int main(){
	char s[110];
	char c;
	int i=0;
	while(scanf("%c",&c)!=EOF){
		s[i++] = c;
	}
	int l = strlen(s),j,k,m,t;
	for(i=0;i<=26;i++){
		char t[110]={'a'};
		for(j=0;j<l;j++){
			if(s[j]>='a'&&s[j]<='z'){
				t[j] = d[(s[j]-'a'+i)%26];
			}
			else t[j] =s[j];
		}
		int a=0,b=0,c=0;
		for(j=0;j<l-2;j++){
			if(t[j]=='t'&&t[j+1]=='h'){
				if(t[j+2]=='e'&&!(t[j+3]>='a' && t[j+3]<='z')){
					a++;
				}
				if(t[j+2]=='i'&&t[j+3]=='s'&&!(t[j+4]>='a'&&t[j+4]<='z')){
					b++;
				}
				if(t[j+2]=='a'&&t[j+3]=='t'&&!(t[j+4]>='a'&&t[j+4]<='z')){
					c++;
				}
			}
		}
		if(a&&b&&c)break;
	}
	for(j=0;j<l;j++){
		if(s[j]>='a'&&s[j]<='z'){
			printf("%c",d[(s[j]-'a'+i)%26]);
		}
		else printf("%c",s[j]);
	}
	puts("");
	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;
vector<string> res;

int main()
{
  while(cin >> str) res.pb(str);

  bool ok = false;
  rep(k, 26){
    vrep(v, res) rep(i, v->size()) if((*v)[i] >= 'A' && (*v)[i] <= 'z') (*v)[i] = 'a' + ((*v)[i] + 1) % 26;
    vrep(v, res) if(*v == "the" || *v == "this" || *v == "that") ok = true;
    if(ok){
      cout << res << endl;
      break;
    }
  }

  /*
  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;
}