C :

#include<stdio.h>
#include<string.h>
int main()
{
	char a[100];
	gets(a);
	int f=strlen(a);
	for(int i=0;i<f;i++){
		if(a[i]<='z'&&a[i]>='a'){
			if(a[i]<=('a'+'z')/2){
				a[i]='z'-(a[i]-'a');
			}
			else{
				a[i]='a'+('z'-a[i]);
			}
		}
		if(a[i]<='Z'&&a[i]>='A'){
			if(a[i]<=('A'+'Z')/2){
				a[i]='Z'-(a[i]-'A');
			}
			else{
				a[i]='A'+('Z'-a[i]);
			}
		}
	}
	puts(a);
	return 0;
} 

C++ :

#include <iostream>
#include <cstring>
using namespace std;

int main(){
	char s[1000];
	gets(s);
	int i;
	for (i = 0;i < strlen(s);i++){
		if (s[i] >= 'A' && s[i] <= 'Z'){
			s[i] = 'Z' - s[i] + 65;
		}else if (s[i] >= 'a' && s[i] <= 'z'){
			s[i] = 'z' - s[i] + 97;
		}
	}
	cout<<s;
}

Java :

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String str = sc.nextLine();
		String Str1 = "";
		for(int i = 0 ;i < str.length();i++){
			if(str.charAt(i)>='A' && str.charAt(i)<='Z'){
				Str1 += (char)('Z' - (str.charAt(i) - 'A'));
			}else if(str.charAt(i)>='a' && str.charAt(i)<='z'){
				Str1 += (char)('z' - (str.charAt(i) - 'a'));
			}else{
				Str1 += str.charAt(i);
			}
		}
		System.out.println(Str1);
	}
}

Python :

def fanma(c):
    if  c.isalpha():
        if c.isupper():
            n=ord(c)-ord('A')
            return chr(ord('Z')-n)
        else:
            n=ord(c)-ord('a')
            return chr(ord('z')-n)
    else:
        return c
str1=input().strip()
for item in str1:
    print(fanma(item),end="")