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 <cmath>
#include <iostream>
#include <cstdio>
#include <ctype.h>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <iomanip>
#include <set>
#include <stack>
#include <queue>
#include <vector>
#include <sstream>


using namespace std;



string shift_str(string str, int num)
{
	int ascii;
	string ret;
	
	for (int i=0; i<str.length(); i++)
	{
		ascii = (int)str[i];
		//cout << "ascii = " << ascii << endl;
		
		if (!('a' <= ascii && ascii <= 'z'))
		{
			ret += ascii;
		} else {
			ascii += num;
			if (ascii > 'z')
			{
				ret += ((ascii - 'z') + 'a' - 1);
			} else {
				ret += ascii;
			}
		}
		
	}
	
	return ret;
}
//the this that


int main()
{
	string str;
	string ret;
	
	while (getline(cin, str))
	{
		for (int i=1; i<=26; i++)
		{
			ret = shift_str(str, i);
			if ( ret.find("the", 0) != string::npos
				|| ret.find("this", 0) != string::npos
				|| ret.find("that", 0) != string::npos )
			{
				//cout << "i = " << i << endl;
				cout << ret << endl;
				break;
			}
		}
	}
	
	return 0;
}

C++: #include <stdio.h>
using namespace std;

int main() {
	string st;
	string w[3]={"the","this","that"};
	int wn[3]={3,4,4},k,i,j,s,f;
	while(getline(cin,st)) {
    k=0;
	while(k<st.size()) {
		for (i=0;i<3;i++) {
			s=0; f=0;
			if (st.size()<k+wn[i]) break;
			for (j=0;j<wn[i]-1;j++) if ((w[i][j]-w[i][j+1])==(st[k+j]-st[k+j+1])) s++;
			if (s==wn[i]-1) { f=1; i=5;}
		}
		if (f==1) break;
		k++;
		}
	if (f==0) cout << st; else {
	for (i=0;i<st.size();i++) if ((st[i]>='a' && st[i]<='z')) cout << (char)(st[i]-(st[k]-'t')) ; else cout << st[i];
	}	
	cout << endl;
	}
    return 0;
	}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <string>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <istream>
#include <sstream>
#include <iomanip>
#include <iterator>
#include <climits>
using namespace std;

typedef ostringstream OSS;
typedef istringstream ISS;

typedef vector<int> VI;
typedef vector< VI > VVI;

typedef long long LL;

typedef pair<int, int> PII;
typedef vector<PII> VPII;

#define X first
#define Y second

string nextConvert(string s) {
	transform(s.begin(), s.end(), s.begin(), [](char c)->char{
			if (islower(c)) return (c - 'a' + 1) % 26 + 'a';
			if (isupper(c)) return (c - 'A' + 1) % 26 + 'A';
			else 			return c;
		});
	return s;
}

bool check(string s) {
	vector<string> targets({"the", "this", "that"});

	for (auto &target : targets) {
		if (s.find(target) == string::npos) {
			return false;
		}
	}

	return true;
}

int main(void) {
	string s;

	while (getline(cin, s)) {
		for (int i = 0; i < 26; i++) {
			s = nextConvert(s);
			if (check(s)) {
				cout << s << endl;
				break;
			}
		}
	}

	return 0;
}

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

int main(){
	string str[100];
	int k = 0;
	int zure[100];
	bool flag[100] = {false};
	while(getline(cin, str[k])){
		for(int j = 0; j < 26; j++){
			for(int i = 0; i < str[k].size()-2; i++){
				if(str[k][i] == 't'+j && str[k][i+1] == 'h'+j && str[k][i+2] == 'e'+j){
					zure[k] = j;
					flag[k] = true;
					break;
				}
			}
			if(flag[k] == true){
				k++;
				break;
			}
			for(int i = 0; i < str[k].size()-3; i++){
				if(str[k][i] == 't'+j && str[k][i+1] == 'h'+j && str[k][i+2] == 'i'+j && str[k][i+3] == 's'+j){
					zure[k] = j;
					flag[k] = true;
					break;
				}
			}
			if(flag[k] == true){
				k++;
				break;
			}
			for(int i = 0; i < str[k].size()-3; i++){
				if(str[k][i] == 't'+j && str[k][i+1] == 'h'+j && str[k][i+2] == 'a'+j && str[k][i+3] == 't'+j){
					zure[k] = j;
					flag[k] = true;
					break;
				}
			}
			if(flag[k] == true){
				k++;
				break;
			}
		}
		k++;
	}
	for(int j = 0; j < k; j++){
		for(int i = 0; i < str[j].size(); i++){
			if(str[j][i] >= 'a' && str[j][i] <= 'z'){
				str[j][i] = str[j][i]-zure[j];
				if(str[j][i] < 'a'){
					str[j][i] = str[j][i]+26;
				}
				cout << str[j][i];
			}
			else{
				cout << str[j][i];
			}
		}
		cout << endl;
	}
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <cassert>

using namespace std;


#define all(c) ((c).begin()), ((c).end())
#define debug(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define present(c, e) ((c).find((e)) != (c).end())
#define cpresent(c, e) (find(all(c), (e)) != (c).end())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i, a, b) for (int i = (int)(a); i <= (int)(b); i++)

#define mp make_pair
#define fst first
#define snd second
#define pb push_back


const double EPS = 1e-10;


typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef complex<double> P;


int main(){
	string s; getline(cin, s);
	rep (i, 26) {
		rep (j, s.size()) if (isalpha(s[j])) {
			s[j]++;
			if (s[j] > 'z') s[j] = 'a';
		}
		if (s.find("the") != -1 || s.find("this") != -1 || s.find("that") != -1) break;
	}
	cout << s << endl;
	
	return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <cstring>

using namespace std;

char data[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'};
char trans[100];
char mozi;
int position=0;
int zoom;
int first_check=0,first_position=0;
int now;
char result;

int main(){
	while(scanf("%c",&mozi) != EOF){
		for(int i=0;i<26 && first_check == 0;i++){
			if(mozi == data[i]){
				first_position = i;
				zoom = first_position - 19;
				first_check = 1;
			}
		}




		if(mozi == ' ' || mozi == '.' || mozi == '\n'){
			if(mozi == ' ' || mozi == '.'){
				trans[position] = mozi;
				position++;
			}

			if(mozi == '\n'){
				printf("%s",trans);
				first_check = 0;
				position = 0;
				memset(trans,'\0',sizeof(trans));
			}
		}else{
			for(int i=0;i<26;i++){
				if(data[i] == mozi){
					now = i;
					break;
				}
			}

			trans[position] = data[now - zoom];
			position++;

		}
	}
}

C++: #include<iostream>
#include<string>
using namespace std;
string S; char T[29] = "abcdefghijklmnopqrstuvwxyz. "; int x[100000];
int main() {
	getline(cin, S);
	for (int i = 0; i < 100000; i++) { x[i] = 100000; }
	for (int i = 0; i < S.size(); i++) {
		for (int j = 0; j < 28; j++) {
			if (T[j] == S[i]) {
				x[i] = j;
			}
		}
	}
	for (int h = 0; h < 26; h++) {
		if (S.find("this") != string::npos){
			goto E;
		}
		if (S.find("that") != string::npos) {
			goto E;
		}
		if (S.find("the") != string::npos) {
			goto E;
		}
		for (int i = 0; i < S.size(); i++) {
			if (S[i] >= 'a') {
				if (S[i] == 'z') {
					S[i] -= 25;
				}
				else {
					S[i]++;
				}
			}
		}
	}
E:;
	cout << S << endl;
}