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 <iostream>
#include <string>
#include <vector>

using namespace std;

int main() {
	string str;
	string in;
	vector<string> s;
	while (cin >> in) s.push_back(in);
	for (int i=0; i<(int)s.size(); i++) {
		str += s[i];
		if (i<(int)s.size()-1) str += " ";
	}
	
	for (int i=0; i<26; i++) {
		for (int j=0; j<(int)str.size(); j++) {
			if (str[j] == '.' || str[j] == ' ') continue;
			str[j] = str[j] + i;
			if (str[j] >= 'z') str[j] = 'a' + str[j] - 'z';
		}
		if (str.find("the")!=str.npos || str.find("this")!=str.npos || str.find("that")!=str.npos) break;
	}
	
	cout << str << endl;
	
	return 0;
}

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

int main(void)
{
	char str[100];
	int num, num2;
	int i;
	
	while (fgets(str, 100, stdin) != NULL){
		num = 't' - str[0];
		i = 0;
		while (str[i] != '\0'){
			if (str[i] >= 'a' && str[i] <= 'z'){
				str[i] += num;
				if (str[i] > 'z'){
					num2 = str[i] - 'z';
					str[i] = num2 + 'a';
				}
				else if (str[i] < 'a'){
					num2 = 'a' - str[i];
					str[i] = 'z' - num2;
				}
			}
			i++;
		}
		printf("%s", str);
	}
	
	printf("\n");
	
	return (0);
}

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

// determine whether it is "the","this" or "that"
char get_shift(string w) {
	char sh = 't' - w.front();
	for_each(w.begin(),w.end(),[sh](char &c) {
		c += sh;
		if (c > 'z') {
			c -= (char)26;
		} else if (c < 'a') {
			c += (char)26;
		}
	});
	if (w.find("the") == string::npos && w.find("this") == string::npos && w.find("that") == string::npos) {
		sh = '\0';
	}
	return sh;
}

int main() {
	string s;
	while (getline(cin,s)) {
		istringstream stream(s);
		string w;
		char sh;
		while (stream >> w) {
			while (!w.empty() && w.front() == '.') {
				w.erase(0,1);
			}
			while (!w.empty() && w.back() == '.') {
				w.pop_back();
			}
			if (!w.empty()) {
				if ((sh = get_shift(w)) != '\0') {
					break;
				}
			}
		}
		for_each(s.begin(),s.end(),[sh](char &c) {
			if (c >= 'a' && c <= 'z') {
				c += sh;
				if (c > 'z') {
					c -= (char)26;
				} else if (c < 'a') {
					c += (char)26;
				}
			}
		});
		cout << s << endl;
	}
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <vector>


int main()
{
	char s[81];
	while (fgets(s, 81, stdin) != NULL)
	{
		for (int i = 0; i < 26; ++i)
		{
			char decoded[81];
			for (int j = 0; s[j] != '\0'; ++j)
				decoded[j] = islower(s[j]) ? 'a'+(s[j]-'a'+i)%26 : s[j];
			decoded[strlen(s)] = '\0';
			if (strstr(decoded, "the")
				|| strstr(decoded, "this")
				|| strstr(decoded, "that"))
			{
				puts(decoded);
				break;
			}
		}
	}
	return 0;
}

C++: /*
C++ ???????????????????????????????????¬??????
??????AOJ-ITP1??????????????????
*/
#define _USE_MATH_DEFINES

#include <iostream> // ?¨??????\??????
#include <fstream>  // ??????????????\??????
#include <string>   // ???????????¢???
#include <vector>   // ???????????????
#include <cmath>    // ??°??????
#include <iomanip>  // stream???????????¢???
#include <algorithm>// max??¢??°??????

using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;        // ????´???°????????????????????????
using std::fixed;         // ???????????????????¨???????????????????????????????
using std::setprecision;  // ?????°????°???°?????\???????????°????????????????????¨????????\???

int main() {
	string str;		// ????????????????????????????´???????
	string trans;	// ????????????????????????????´???????
	
	while (std::getline(cin, str))
	{
		trans.clear();
		trans.resize(80);
		// n?????????????????????????????§7????????????
		for (int i = -8;; i++)
		{
			for (size_t j = 0; j < str.size(); j++)
			{
				// ???????????????????????????????????????
				if (str[j] == ' ' || str[j] == '.')
				{
					trans[j] = str[j];
				}
				else
				{
					trans[j] = str[j] + i;
				}
			}
			// ?????????????????????find??¢??°???????????¨??????
			// ???????????£??????????¨??????????????????£????????????????????????
			if (!trans.find("this") || !trans.find("the") || !trans.find("that"))
			{
				cout << trans << endl;
				break;
			}
		}

	}
	return 0;
}

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

using namespace std;
string s;
char decrypt[50];
int key,i;

int main(){
    while(getline(cin,s)){
        const char *encrypt = s.c_str();
        while(encrypt[i] != '\0'){
            if(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 <= 50){
            decrypt[i] = '\0';
            i++;
        }
        printf("%s\n", decrypt);
    }
    return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;
int main()
{
    string s;
    while(getline(cin,s))
	{
        for(int i=0;i<26;++i)
		{
            for(int j=0;j<s.size();++j) 
				if('a'<=s[j]&&s[j]<='z')
					{
						s[j]=((s[j]-'a'+1)%26+'a');
				}
            if(s.find("the")!=-1||s.find("this")!=-1||s.find("that")!=-1)break;
        }
        cout<<s<<endl;
    }
    return 0;
}

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(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;
}