Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		var result string
		line := scanner.Text()
		key := make(map[string]string)

		var i int32
		for ; i < 52; i++ {
			makeKey(key, i)
			result = decode(key, line)

			if strings.Contains(result, "the") {
				break
			} else if strings.Contains(result, "this") {
				break
			} else if strings.Contains(result, "that") {
				break
			}
		}

		fmt.Println(result)
	}
}

func makeKey(key map[string]string, shift int32) {
	for i := 'a'; i <= 'z'; i++ {
		cipher := (i + shift)
		if cipher > 'z' {
			cipher = cipher%'z' + 'a' - 1
		} else if cipher < 'a' {
			cipher = cipher + ('z' - 'a') + 1
		}
		key[string(i)] = string(cipher)
	}
}

func decode(key map[string]string, cipher string) string {
	var result string
	for _, v := range cipher {
		if key[string(v)] != "" {
			result += key[string(v)]
		} else {
			result += string(v)
		}
	}
	return result
}

C++: 

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<math.h>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#include<set>
#include<map>
#include<stdlib.h>
#include<iomanip>

using namespace std;

#define ll long long
#define ld long double
#define EPS 0.0000000001
#define INF 1e9
#define MOD 1000000007
#define rep(i,n) for(i=0;i<n;i++)
#define loop(i,a,n) for(i=a;i<n;i++)
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)

typedef vector<int> vi;
typedef pair<int,int> pii;

int main(void) {
  int i,j,k;
  string s;
  while(getline(cin,s)){
    int n=0;
    rep(i,s.size())if(s[i]==' ')n++;
    n++;
    vector<string> word(n);
    i=0;
    rep(j,n){
      while(s[i]>='a' && s[i]<='z')
	word[j].push_back(s[i]),i++;
      i++;
    }
    rep(k,26){
      bool c=false;
      rep(i,n)rep(j,word[i].size())
	if(word[i][j]=='z')word[i][j]='a';
	else word[i][j]=word[i][j]+1;
      rep(i,n)
	if(word[i]=="the" || word[i]=="this" || word[i]=="that"){
	  c=true;break;
	}
      if(c){
	rep(i,n){
	  if(i)cout<<" ";
	  cout<<word[i];
	}
	cout<<"."<<endl;
	break;
      }
    }
  }
}

C++: /*
NOTE :
*min_element(.begin(),.end())
*max_element(.begin(),.end())
stack push pop top
queue push pop front
priority_queue<> pq
 push()  pop() size()  top()
map<>
 find() begin() end() insert(map<>::value_type())
pair<>
sort(.begin(), .end())
sort(arr, arr+N)
sort(a, a+N, greater<int>())
binary_search(vc.begin(), vc.end(), x)  //binary_search???true, false?????????
vector<int>::iterator lit = lower_bound(vc.begin(), vc.end(), x);
  lower_bound?????????????????????"??\???"????????????????????????????????????????????¬???????????????
vector<int>::iterator uit = upper_bound(vc.begin(), vc.end(), x);
  upper_bound????????????????????????"?¶???????"?????????????????????????????????????????¬???????????????
*/
#include <iostream>
#include <cstdio>
#include <climits>
#include <cmath>
#include <cassert>
#include <sstream>
#include <algorithm>
#include <valarray>
#include <utility>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <map>
#include <set>

#define MAX 100
#define INF 1<<20
#define LLINF 10e12 // 1<<31 // 2^31
#define REP(i,n) for(int i=0;i<n;i++)
#define REP2(i,a,n) for(int i=(a);i<(n);i++)
#define SET(a,c) memset(a,c,sizeof a)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define FOREACH(i,c) for(auto (i) : (c))
#define BIT(i,j) ((i)>>(j))&1
#define ALL(o) (o).begin(), (o).end()
#define ERASE(o) (o).erase(unique(ALL((o))), (o).end());

using namespace std;
typedef long long ll;
typedef valarray<int> array_t;
/////
string key[3] =
{
  "the",
  "this",
  "that"
};
/////
int caeser(string S)
{
  int n = S.length();
  REP(i,26)
  {
    string tmp;
    REP(j,n)
    {
      if(S[j] == '.') continue;
      tmp += ((S[j]-'a'+i)%26)+'a';
    }
    REP(k,3) if(tmp == key[k]) return i;
  }
  return -1;
}

void decode(string &S,int t)
{
  if(t < 0) return;
  int n = S.length();
  REP(i,n)
  {
    if(S[i] == '.') continue;
    S[i] = ((S[i]-'a'+t)%26)+'a';
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  // FROM HERE

  string str;
  while(getline(cin,str))
  {
    int t, n;
    string tmp;
    vector<string> data;
    istringstream stream(str);
    while(getline(stream,tmp,' ')) data.push_back(tmp);
    n = data.size();
    REP(i,n) if((t=caeser(data[i]))!=-1) break;
    REP(i,n) decode(data[i],t);
    REP(i,n)
    {
      printf("%s",data[i].c_str());
      printf("%s",(i!=n-1)?" ":"\n");
    }
  }
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
char a[53]="abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
int main(){
    char str[81];
    for(int i=0;i<81;i++)str[i]=0;
    for(int i=0;i<80;i++){
        str[i]=getchar();
        if(str[i]=='.')break;
    }
    int len=strlen(str);
    for(int i=0;i<26;i++){
        char cpy[81];
        strncpy(cpy,str,81);

        for(int j=0;j<len;j++){
            if(str[j]==' ' || str[j]=='.')continue;
            cpy[j]=a[cpy[j]-'a'+i];
        }
        bool f=false;
        for(int j=0;j<len-2;j++){
            if(!strncmp(cpy+j,"the",3))f=true;
            if(!strncmp(cpy+j,"this",4))f=true;
            if(!strncmp(cpy+j,"that",4))f=true;
        }
        if(f){
            cout<<cpy<<endl;
            break;
        }
    }
    return 0;


}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main(void){
        string a;
        bool flg=0;
        while(getline(cin,a)){
            if(a[0]==EOF)flg=1;break;

            for(int i=0;i<26;i++){
                if(a.find("the")!=string::npos||a.find("this")!=string::npos||a.find("that")!=string::npos){
                    cout<<a<<endl;break;
                }
                else
                    for(int i=0;i<a.length();i++){
                        if(a[i]>='a'&&a[i]<='y')a[i]++;
                        else if(a[i]=='z')a[i]='a';
                    }
            }
        }
    return 0;
}

C++: #include<iostream>
#include<string.h>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#define li long long int
#define ld long long double
#define PI 3.1415926535897932384626
#define EPS 0.0000000001
#define rep(i,n) for(i=0;i<n;i++)
using namespace std;
typedef pair<int, int> P;

char str[85];
char word[3][5]={"the","this","that"};
char sent[80][80]={};
int main()
{
  bool ans=false;
  while(1){
    int i=0,j=0;
    int num=0;
    gets(str);
    for(i=0;num<strlen(str);i++){
      for(j=0;;j++){
	sent[i][j]=str[num];
	num++;
	if(sent[i][j]==' '){
	  sent[i][j]='\0';
	  break;
	}
	if(sent[i][j]=='\0')break;
      }
    }
    //cout<<i<<endl;
    int gap,k,l;
    
    rep(gap,26){
      rep(k,i) rep(l,strlen(sent[k])){
	if(sent[k][l]>='a' && sent[k][l]<'z')
	   sent[k][l]++;//??????????????????
	else if(sent[k][l]=='z')
	  sent[k][l]='a';
      	//cout<<sent[k][l];//debug
      }
      // cout<<endl;//debug
      rep(k,i)
	if(strcmp(sent[k],word[0])==0 || strcmp(sent[k],word[1])==0 
	   || strcmp(sent[k],word[2])==0){
	  rep(l,i){
	    for(int a=0;a<strlen(sent[l]);a++)
	      cout<<sent[l][a];
	    if(l<i-1)
	      cout<<" ";
	    else
	      cout<<endl;
	  }
	  ans=true;
	  break;
	}
      if(ans)break;
    }
  }
}