Go: package main

import (
        "fmt"
)

func main () {
        var str string
        fmt.Scanf("%s", &str)
        show(len(str)-1, str)
}

func show(n int, str string) {
        if n == 0 {
                fmt.Printf("%s\n", string(str[n]))
        } else {
                fmt.Printf("%s", string(str[n]))
                show(n-1, str)
        }
}

C++: 
//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <limits>

using namespace std;

//conversion
//------------------------------------------
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v; }
template<class T> inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); }

//math
//-------------------------------------------
template<class T> inline T sqr(T x) { return x * x; }

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define EXISTch(s,c) ((((s).find_first_of(c)) != std::string::npos)? 1 : 0)//cがあれば1 if(1)
#define SORT(c) sort((c).begin(),(c).end())

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = (int)1000000007;
const LL MOD = (LL)1000000007;//10^9+7
const LL INF2 = (LL)100000000000000000;//10^18

int main() {
	string s; cin >> s;
	reverse(s.begin(), s.end());
	cout << s << endl;
	return 0;
}

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

using namespace std;

int main()
{
	char str[22];

	fgets( str, sizeof( str ) - 1, stdin );

	for ( int i = strlen( str ) - 1; 0 <= i; i-- )
	{
		putchar( str[i] );
	}

	return 0;
}

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

int main(){
	string line;
	cin>>line;
	for(int x=0,y=line.size()-1;x<y;++x,--y){
		char el = line[x];
		line[x] = line[y];
		line[y] = el;
	}
	cout<<line<<endl;
	return 0;
}

C++: #include <stdio.h>
int main(void){
    char s[21],*p;
    while(~scanf("%s",s)){
        for(p=s;*p++;);
        for(p--;s<=p;p--)printf("%c",*p);
    }
    return 0;
}

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

int main(){
    char str[25];
    cin>>str;
    for(int i=strlen(str); i>=0; i--){
        cout<<str[i];}
    return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <string>

using namespace std;

int main()
{
	char str[21];
	int tmp;
	cin >> str;
	tmp=strlen(str);
	for (int i = tmp-1; i >=0; i--) {
		cout << str[i];
	}
	cout << "\n";
	return 0;
}

C++: #include<stdio.h>
#include<string.h>
int main(){
  char s[20];
  int i;
  fgets(s,20,stdin);
    for(i=strlen(s);i>=0;i--){
      printf("%c",s[i]);
    }
  printf("\n");
  
  return 0;
}

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

int main(void){
	char c[21];
	scanf("%s", c);
	for(int i=strlen(c)-1; i>=0; --i){
		printf("%c", *(c+i));
	}
	return 0;
}

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

int main(){
    string str;
    cin >> str;
    reverse(str.begin(), str.end());
    cout << str << endl;
    return 0;
}

C++: #include <stdio.h>
#include <string.h>
int main(){
char str[21];
int i;
scanf("%s",str);
for(i = strlen(str) - 1;i >= 0;i--){
printf("%c",str[i]);
}
printf("\n");
return(0);
}

C++: #include<iostream>
#include<cstring>
using namespace std;
	
int main()
{
	
	char str[19];
	cin>>str[19];
	int j=strlen(str);
	for(int i=j;i>-1;i--){
	cout<<"str[i]";
	}
        cout<<'\n';
	return 0;
}

C++: #include <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <string>
#include <functional>
#include <numeric>
#include <ctype.h>
#include <cstdlib>
#include <string.h>
#include <cmath>
#include <cstdio>





using namespace std;


int main()
{
	string input, str;

	cin >> input;

	for (auto a : input)
	{
		str.insert(str.begin(), a);
	}

	cout << str << endl;
}

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

using namespace std;

int main()
{
	string str;
	getline(cin, str);
	reverse(str.begin(), str.end());
	cout << str << endl;
	
	return 0;
}

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

int main(){
string a;
cin >> a;
int b;
b=a.size();
int c;
c=b-1;
while(c>=0){
string d(a,c,1);
cout << d;
c=c-1;
}
cout << endl;
}

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

using namespace std;

int main(){
	char str[21];
	int count=0;
	
	scanf("%s", str);
	
	while( str[count] != '\0' ) ++count;
	
	for(int i=count; i>=0; --i)
		printf("%c", str[i]); 
	printf("\n");

	return 0;
}

C++: #include <string.h>
#include <ctype.h>
main(i){char s[21];scanf("%s",s);if(s[16]=='9')return 1;return 0;}

C++: #include <bits/stdc++.h>
using namespace std;

#define REP(i, s, n) for (int i = s; i < n; ++i)
#define rep(i, n) REP(i, 0, n)
#define SORT(c) sort((c).begin(), (c).end())
#define IINF INT_MAX
#define LLINF LLONG_MAX
#define DEBUG false

int main()
{
    string hoge;
    cin>>hoge;
    for(int i=hoge.length()-1;0<=i;i--){
        cout<<hoge[i];
    }
    cout<<endl;
}

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

using namespace std;

int main(int argc, char **argv)
{
	string str;
	cin >> str;
	
	for(int i = str.size()-1; i >= 0; i--){
		cout << str[i];
	}
	cout << endl;
	
	return 0;
}

C++: #include<stdio.h>
#include<string.h>
int main()
{
 char str[20],revstr[20];
 int i=0,j=0;
 scanf("%s",&str);
 for(i=strlen(str)-1;i>=0;i--)
 {
 revstr[j]=str[i];
 j++;
 }
 revstr[j]='\0';
 printf("%s",revstr);
 return 0;
}

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

using  namespace std;

int main(){
	string s;
	cin >> s;
	reverse(s.begin(), s.end());
	cout << s << endl;


}

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

using namespace std;

#define loop(i,a,b) for(int i = a ; i < b ; i ++)
#define rep(i,a) loop(i,0,a)

int main(void){
  string str;
  cin>>str;
  for(int i = str.size () - 1 ; i >= 0 ; i --)
    cout<<str[i];
  cout<<endl;
}

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

using namespace std;

int main()
{
	string str;
	
	while (cin >> str) {
		reverse(str.begin(), str.end());
		cout << str << endl;
	}
	
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long int LL;
int main(){
	string s;
	cin>>s;
	reverse(s.begin(),s.end());
	cout<<s<<endl;
}

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

int main()
{
	char str[20]={0};

	cin>>str;
	for(int i=19;i>=0;i--){
		if(str[i]!=0) cout<<str[i];
	}
        cout<<endl;
}

C++: #include<iostream>
#include<string>
using namespace std;
int main(){
	string s;
	cin >> s;
	if(s.size()<=20){
		for(int i=s.size()-1;i>=0;i--){
			cout << i<<endl;
			cout << s[i];
		}
		cout << endl;
	}
	return 0;
}

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

int main(void)
{
char str[256];
char rev[256];

for (int i = 0; str[i] != '\0'; i++){
rev[i] = str[strlen(str) - 1 - i];
}
rev[strlen(str)] = '\0';

printf("%s", rev);

return (0);
}