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<cstdio>
#include<cctype>
#include<cstring>
using namespace std;
int main(){
    int f = 0;
    char str[10000] = {0};
    while(scanf("%[^\n]",str)!=EOF){
        fflush(stdin);
        for(int i = 0;i <= 25; i++){
            for(int j = 0;j < strlen(str); j++){
                if(str[j] == ' ' || str[j] == '.')continue;
                str[j]++;
                if(str[j] > 122)str[j] = str[j]-25;
            }
            for(int j = 0;j < strlen(str); j++){
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'e')goto hoge;
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'i' && str[j+3] == 's')goto hoge;
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'a' && str[j+3] == 't')goto hoge;
            }
        }
        for(int i = 0;i < strlen(str); i++){
            if(str[i] == ' ' || str[i] == '.')continue;
            str[i] -= 25;
        }
        for(int i = 0;i <= 25; i++){
            for(int j = 0;j < strlen(str); j++){
                if(str[j] == ' ' || str[j] == '.')continue;
                str[j]--;
                if(str[j] < 97)str[j] = str[j]+25;
            }
            for(int j = 0;j < strlen(str); j++){
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'e')goto hoge;
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'i' && str[j+3] == 's')goto hoge;
                if(str[j] == 't' && str[j+1] == 'h' && str[j+2] == 'a' && str[j+3] == 't')goto hoge;
            }
        }
        hoge:
        printf("%s\n",str);
        memset(str,0,sizeof(str));
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define NCLR(a) memset((a), -1 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
typedef complex<double> P;
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 1000000007;
static const int INF = 1 << 30;
static const LL LL_INF = 1152921504606846976;
static const int dx[] = { -1, 0, 1, 0, 1, -1, 1, -1 };
static const int dy[] = { 0, -1, 0, 1, 1, 1, -1, -1 };

string str;

int main() {
	string str_copy;
	set<string> s;
	getline( cin, str );
	for ( int i = 1; i < 26; i++ ) {
		str_copy = str;
		bool can_continue = false;
		for ( int j = 0; j < str_copy.size(); j++ ) {
			if ( str_copy[ j ] >= 'a' && str_copy[ j ] <= 'z' ) {
				str_copy[ j ] += 26;
				str_copy[ j ] -= i;
				str_copy[ j ] = ( ( str_copy[ j ] - 'a' ) % 26 ) + 'a';
				if ( str_copy[ j ] < 'a' || str_copy[ j ] > 'z' ) {
					can_continue = true;
					break;
				}
			}
		}
		if ( s.count( str_copy ) ) {
			continue;
		}
		s.insert( str_copy );
		if ( can_continue ) {
			continue;
		}
		bool is_can = false;
		for ( int j = 0; j < str_copy.size() - 2; j++ ) {
			if ( str_copy.substr( j, 3 ) == "the" ) {
				is_can = true;
				break;
			}
		}
		for ( int j = 0; j < str_copy.size() - 3; j++ ) {
			if ( str_copy.substr( j, 4 ) == "that" || str_copy.substr( j, 4 ) == "this" ) {
				is_can = true;
				break;
			}
		}
		if ( is_can ) {
			break;
		}

	}
	printf( "%s\n", str_copy.c_str() );
	return 0;
}

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

int main(){
	char input[81],str[50][81];
	const char cmp[3][5]={"that","this","the"};
	int pos=0,last_pos=0,i,j,k,diff;

	while(fgets(input,81,stdin)!=NULL){;
		last_pos=0;
		pos=0;
		for(i=0;input[i]!='\0';i++){
			if(input[i]==' ' || input[i]=='.' || input[i]=='\n'){
				for(j=last_pos;j<i;j++){
					str[pos][j]=input[j];
				}
				str[pos][j]='\0';
				pos++;
				last_pos=i+1;
			}
		}

		for(i=0;i<pos;i++){
			for(j=0;j<3;j++){
				diff=str[i][0]-cmp[j][0];
				for(k=1;str[i][k]!='\0' && cmp[j][k]!='\0';k++){
					if(diff!=str[i][k]-cmp[j][k]){
						break;
					}
				}
				if(str[i][k]=='\0' && cmp[j][k]=='\0'){
					j=3;i=pos;
				}
			}
		}

		for(i=0;input[i]!='\n';i++){
			if(input[i]!='.' && input[i]!=' '){
				input[i]-=diff;
			}
		}

		printf("%s",input);
	}

	return 0;
}

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

int main(void)
{


	char str[100];
	while(gets(str)){

	while(!strstr(str, "this") && !strstr(str, "the") && !strstr(str, "that")){
		for(int i = 0; i < strlen(str); i++){
			if(str[i] >= 'a' && str[i] <= 'a'+26)
				str[i] = 'a' + (str[i] - 'a' + 1) % 26;
		}
	}

	printf("%s\n", str);
	}

	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
vector<string> split(string &s, char delimiter){
  vector<string> res;
  int prev_split_point = 0;
  for (int i = 0; i < s.length(); i++) {
    while(s[i] != delimiter && i < s.length())i++;
    string add = s.substr(prev_split_point, i - prev_split_point);
    if(!add.empty())res.push_back(add);
    prev_split_point = i + 1;
  }
  return res;
}

int main(int argc, char *argv[]){
  char c[26];
  for (int i = 0; i < 26; i++) {
    c[i] = 'a' + i;
  }
  vector<string> vs;
  string s;
  string ans[] = {"this", "that", "the"};
  vector<string> tmp;
  while(getline(cin, s)){
    vs = split(s, ' ');
    int n = vs.size();
    for (int k = 0; k < 26; k++) {
      tmp = vs;
      for (int i = 0; i < vs.size(); i++) {
        for (int j = 0; j < vs[i].length(); j++) {
          if('a' <= tmp[i][j] && tmp[i][j] <= 'z')
            tmp[i][j] = c[(vs[i][j] - 'a' + k) % 26];
        }
      }
      for (int i = 0; i < 3; i++) {
        for (int j = 0; j < tmp.size(); j++) {
          if(tmp[j] == ans[i]){k = 50, i = 10, j = 1000;}
        }
      }
    }
    for (int i = 0; i < tmp.size(); i++) {
      std::cout << tmp[i];
      if(i == tmp.size() - 1)std::cout << std::endl;
      else std::cout << " ";
    }
  }
  return 0;
}