Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

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 scanner.Scan() {
		infos := strings.Split(scanner.Text(), " ")
		plain := make([]string, len(infos))
		// fmt.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 <iostream>
#include <string>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <sstream>      // std::ostringstream
std::vector<std::string> split(const std::string &str, char sep)
{
	std::vector<std::string> v;
	std::stringstream ss(str);
	std::string buffer;
	while (std::getline(ss, buffer, sep)) {
		v.push_back(buffer);
	}
	return v;
}
using namespace std;
int main() {
	string str;
	string w[3] = { "the","this",  "that" };
	getline(cin, str);

	vector<string> v = split(str, ' ');

	int key;
	bool f = false;

	v[v.size() - 1].pop_back();

	for (int i = 0; i < v.size();i++) {
		for (int j = 1; j < 26;j++) {
			string temp;
			for (int k = 0; k < v[i].size();k++) {
				temp += (v[i][k] - 'a' + j) % 26 + 'a';
			}
			for (int k = 0; k < 3;k++) {
				if (temp == w[k]) {
					f = true;
					key = j;
					break;
				}
			}
			if (f)break;
		}
		if (f)break;
	}

	for (int i = 0; i < v.size();i++) {
			for (int k = 0; k < v[i].size();k++) {
				cout << char((v[i][k] - 'a' + key) % 26 + 'a');
			}
			if (i == v.size() - 1) {
				cout << ".";
			}
			else {
				cout << " ";
			}
	}
	cout << endl;
}

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

int main() {
  string str;
  while(getline(cin,str)) {
    for(int j=0;j<26;j++) {
      if(str.find("the")!=string::npos||str.find("this")!=string::npos||str.find("that")!=string::npos) {
        cout << str << endl;
        break;
      }
      for(unsigned int i=0;i<str.size();i++) {
        if(str[i] <= 'z' && 'a' <= str[i]) {
          str[i] -= 97;
          str[i]++;
          str[i] %= 26;
          str[i] += 97;
        }
      }
    }
  }
}

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

using namespace std;

void caesar(char* a)
{
	for (int i=0; i<strlen(buf); i++) {
		if (c==' ' || c== '.') continue;
		else if (c=='z') buf[i] = 'a';
		else buf[i]++;
	}
}

int main()
{
	char buf[81];
	
	for (int k=0; k<20; k++) {
		fgets(buf, 80, stdin);
		int len = strlen(buf);
		for (int i=0; i<26; i++) {
			if ( (strstr(buf, "the") != NULL) || (strstr(buf, "this") != NULL) || (strstr(buf, "that") != NULL) ) {
				cout << buf << endl;
				break;
			}
			caesar(buf);
		}
	}
	
	return 0;
}

C++: 
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <stack>
#include <cctype>
#include <complex>
#include <vector>
#include <algorithm>

using namespace std;


bool solve(){
	
	string s;
	while(getline(cin,s)){
		string str[26];
		int num;
		for(int i=0;i<26;i++){
			str[i] = s;
			for(int j=0;j<str[i].size();j++){
				for(int k=0;k<i;k++){
					if(str[i][j]=='.' || str[i][j]==' '){
						continue;
					}
					if(str[i][j] == 'a'){
						str[i][j] = 'z';
					}
					str[i][j]--; 
				}
			}
			
			for(int j=0;j<str[i].size();j++){
				string str_temp, str_temp2;	
				if(j <= str[i].size()-3){
					str_temp  = str[i].substr(j,3);
				}
				if(j <= str[i].size()-4){
					str_temp2 = str[i].substr(j,4);
				}
				if(str_temp=="the" || str_temp2=="this" || str_temp2=="that"){
					num = i;
				}
			}
		}
		
		
		cout<< str[num]<< endl;
	}		
	
	return true;
}

int main(){
	cout.setf(ios::fixed);
	cout.precision(10);
	solve();

	return 0;
}

C++: #include <iostream>
#include <string>
#define REP(i,n) for(int i = 0; i < (n); ++i)
using namespace std;

string Caesar(string str, int shift){
    string ret="";
    REP(i, str.size()){
        if('a'<=str[i] && str[i]<='z') ret += (str[i] - 'a' + shift) % 26 + 'a';
        else ret+=str[i];
    }
    return ret;
}

int main(){
	string str;
	getline(cin, str, '\n');
	REP(i, 26){
		string fix = Caesar(str, i);
    	if( fix.find( "the", 0 ) != string::npos ||
    		fix.find( "this", 0 ) != string::npos ||
    		fix.find( "that", 0 ) != string::npos ){
			cout<<fix<<endl;
			break;
		}
	}
	return 0;
}

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

int main(void)
{
    list<string> input;
    int dec = 0;
    string s;
    while (cin >> s)
    {
        input.push_back(s);

        if (dec == 0)
        {
            int d;
            d = s[0] - 't';

            string t = "";
            for (int i = 0; i < s.length(); i++)
                t += s[i] - d;

            if (t == "the" || t == "this" || t == "that")
                dec = d;
        }
    }
    int n = 0;
    for (list<string>::iterator i = input.begin(); i != input.end(); i++)
    {
        n++;
        string out = *i;
        for (int j = 0; j < out.length(); j++)
        {
            if (out[j] != '.')
            {
                cout << (char)(out[j] - dec);
            }
            else
            {
                cout << '.';
            }
        }
        if(n < input.size()){
            cout << ' ';
        }
    }

    cout << endl;
    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] << endl;
	}
}