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++: #define scanf_s scanf
#define gets_s gets
#include <stdio.h>
#include <string>
#include <iostream>
#include <math.h>
using namespace std;
#define MAX 81
#define _MAX 100
#define ABC 26
int main(void)
{
	int n, s = 0, x, y, r = 0, d;
	char str[MAX];

	while (gets_s(str) != NULL) {
		for (int i = 0; str[i] != '\0'; ++i) {
			if (str[i] - 't' == str[i + 1] - 'h') {
				d = str[i] - 't';
				if ((str[i + 2] - 'a' - d + ABC) % ABC == 'e' - 'a') { break; }
				else if ((str[i + 2] - 'a' - d + ABC) % ABC == 'i' - 'a' && (str[i + 3] - 'a' - d + ABC) % ABC == 's' - 'a') { break; }
				else if ((str[i + 2] - 'a' - d + ABC) % ABC == 'a' - 'a' && (str[i + 3] - 'a' - d + ABC) % ABC == 't' - 'a') { break; }
			}
		}
		for (int i = 0; str[i] != '\0'; ++i) {
			if ('a' <= str[i] && str[i] <= 'z') {
				printf("%c", (str[i] - 'a' - d + ABC) % ABC + 'a');
			}
			else { printf("%c", str[i]); }
		}
		printf("\n");
	}
}

C++: #include <iostream>
#include <cstdio>
#include <vector>
#include <string>
#include <ctype.h>
#include <algorithm>
using namespace std;

#define loop(i,a,b) for(int i=(a); i<(int)(b); i++)
#define rep(i,b) loop(i,0,b)
#define all(c) (c).begin(), (c).end()
 
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;

int main() {
  string s; getline(cin, s);
  int slide = 0;
  rep(i, s.size()-3) {
    if(islower(s[i]) == 0) continue;
    rep(j, 26) {
      string sub;
      rep(k, 4) sub += (s[i+k]-'0'+j+26)%26 + 'a';
      if(sub.substr(0,3) == "the") slide = j;
      else if(sub == "this" || sub == "that") slide = j;
    }
    if(slide != 0) break;
  }
  rep(i, s.size()) {
    if(islower(s[i]) != 0)printf("%c", (s[i]-'0'+slide+26)%26 + 'a');
    else cout << s[i];
  }
  cout << endl;
}

C++: #include <iostream>
#include <string>

using namespace std;

int main()
{
  string stro, str;
  while(getline(cin, stro)){
    for(int i = 0; i < 26; i++){
      str = stro;
      for(int j = 0; j < stro.length(); j++){
	if(str[j] >= 'a' && str[j] <= 'z')
	  if(str[j] + i > 'z')
	    str[j] += i - 26;
	  else
	    str[j] += i;
      }
      std::string::size_type f_the = str.find("the", 0);
      std::string::size_type f_this = str.find("this", 0);
      std::string::size_type f_that = str.find("that", 0);
      if((f_the != string::npos && f_the == 0 && (str[f_the + 3] == ' ' || str[f_the + 3] == '.' || str[f_the + 3] == '\0')) || (f_this != string::npos && f_this == 0 && (str[f_this + 4] == ' ' || str[f_this + 4] == '.' || str[f_this + 4] == '\0')) || (f_that != string::npos && f_that == 0 && (str[f_that + 4] == ' ' || str[f_that + 4] == '.' || str[f_that + 4] == '\0')))
	cout << str << endl;
      else if((f_the != string::npos && (str[(f_the - 1 < 0) ? 0 : f_the - 1] == ' ' || str[(f_the - 1 < 0) ? 0 : f_the - 1] == '.' || str[(f_the - 1 < 0) ? 0 : f_the - 1] == '\n') && (str[f_the + 3] == ' ' || str[f_the + 3] == '.' || str[f_the + 3] == '\0')) || (f_this != string::npos && (str[(f_this - 1 < 0) ? 0 : f_this - 1] == ' ' || str[(f_this - 1 < 0) ? 0 : f_this - 1] == '.' || str[(f_this - 1 < 0) ? 0 : f_this - 1] == '\n') && (str[f_this + 4] == ' ' || str[f_this + 4] == '.' || str[f_this + 4] == '\0')) || (f_that != string::npos && (str[(f_that - 1 < 0) ? 0 : f_that - 1] == ' ' || str[(f_that - 1 < 0) ? 0 : f_that - 1] == '.' || str[(f_that - 1 < 0) ? 0 : f_that - 1] == '\n') && (str[f_that + 4] == ' ' || str[f_that + 4] == '.' || str[f_that + 4] == '\0')))
	cout << str << endl;	 
    }
  }
}

C++: #include <stdio.h>
int check(int a,int b,int c,int d)
{
    //printf("[%d][%d][%d][%d]\n",a,b,c,d);
    if(a != 14)return 0;
    else if(b == 23 && c == 0)return 1;
    else if(b == 1 && c == 10 && d == 0)return 1;
    else if(b == 19 && c == 19 && d == 0)return 1;
    else return 0;
}

int main()
{
    int longth,mem;
    while(1)
    {
        char str[90] = {0};
        int mem1[90] = {0},mem2[90] = {0};
        if(scanf("%c",&str[0]) == -1)return 0;
        if(str[0] >= 'a' && 'z' >= str[0])mem1[0] = str[0] - 'a' + 1;
        for(int i = 1; i < 80; i++)
        {
            scanf("%c",&str[i]);
            if(str[i] == '\n')break;
            longth = i;
            if(str[i] >= 'a' && 'z' >= str[i])mem1[i] = str[i] - 'a' + 1;
        }
        for(int i = 0; i < longth; i++)
        {
            if(mem1[i] == 0);
            else if(mem1[i + 1] != 0)
            {
                if(mem1[i] <= mem1[i + 1])mem2[i] = mem1[i + 1] - mem1[i];
                else mem2[i] = 26 - mem1[i] + mem1[i + 1];
            }
        }
        /*for(int i = 0; i < longth; i++)
        {
            printf("[%d]",mem2[i]);
        }
        printf("\n");*/
        for(int i = 0; i < longth; i++)
        {
            if(mem2[i] == 0);
            else if(i == 0)if(check(mem2[i],mem2[i + 1],mem2[i + 2],mem2[i + 3]))/*printf("%d\n",i);*/if(mem1[i] <= 20)mem = 20 - mem1[i];else mem = 26 - mem1[i] + 20;
            else if(mem2[i - 1] != 0)if(check(mem2[i],mem2[i + 1],mem2[i + 2],mem2[i + 3]))/*printf("%d\n",i);*/if(mem1[i] <= 20)mem = 19 - mem1[i];else mem = 26 - mem1[i] + 20;
        }
        //printf("{%d}\n",mem);
        for(int i = 0; i < longth + 1; i++)
        {
            if(str[i] >= 'a' && 'z' >= str[i])printf("%c",(str[i] - 'a' + mem) % 26 + 'a');
            else printf("%c",str[i]);
        }
        printf("\n");
    }
}