C :

#include<stdio.h>
void main()
{
	int i,n=0;
	for(i = 97;i <= 122;i++){
		printf("%c",i); 
		n++;
		if(n % 13 == 0){
			printf("\n"); 
		} 
	} 
	for(i = 122;i >= 97;i--){
		printf("%c",i); 
		n++;
		if(n % 13 == 0){
			printf("\n"); 
		} 
	} 

   return 0;
}

C++ :

#include <iostream>
using namespace std;
int main (){
	int i;
	char c;
	
	for(i=97;i<=122;i++){
		c=i;
		cout<<c;
		if(i==97+12||i==97+25){
			cout<<endl;
		}
	}
	for(i=122;i>=97;i--){
		c=i;
		cout<<c;
		if(i==122-12||i==97){
			cout<<endl;
		}
	}
}

Pascal :

var
  ch:char;
begin
  for ch:='a' to 'm' do
    write(ch);
      writeln;
         for ch:='n' to 'z' do
           write(ch);
             writeln;
               for ch:='z' downto 'n' do
                 write(ch);
                   writeln;
                      for ch:='m' downto 'a' do
                        write(ch);
                          writeln;
end.

Java :

public class Main{
	public static void main(String[] args) {
		int n=0,m=0;
		for(int i=1;i<=4;i++){
			for(int j=1;j<=13;j++){
				if(n<26){
					System.out.print((char)(97+n));
					n++;
				}else{
					m++;
					System.out.print((char)(97+n-m));
				}
			}
			System.out.println();
		}
	}
}

Python :

num = 0
numt = 0
for i in range(97,123):
    print(chr(i),end='')
    num += 1
    if num == 13:
       print()
print()
for j in range(122,96,-1):
    print(chr(j),end='')
    numt += 1
    if numt == 13:
       print()