#include<stdio.h>
#include<string.h>
#include<ctype.h>
void encode_message(char*message){
    int len =strlen(message);
    for(int i=0;i<len;i++){
        if(!isalpha(message[i]&& message[i]!=' '))
        printf("Invalid Input\n");
        return;
    }
    for(int i=0;i<len;i++){
        if(isalpha(message[i])){
            char base;
            if(islower(message[i])){
                base+'a';
                message[i]=(char)('z'-(message[i]-base));
            }
            else
          base='A';
        message[i]=(char)('z'-(message[i]-base));
        printf("%s\n",message);
    }
    int main(){
        char message1[]="CodeChallenge";
        encode_message(message1);
        char message2[]="Tab Switches";
        encode_message(message2);
        char message3[]="Invalid Input";
        encode_message(message3);
        return 0;

             }