/* file : simpleEncoding.c */
/* author : Oscar Miró (o.miro.i.lopez.feliu@student.rug.nl) */
 
/* Description:
 * Given a series of characters, encodes them. Adds n to their ascii value where n is
 * their position in the sentence.  
 */

#include <stdio.h>
#include <ctype.h>
 
int main(int argc, char *argv[]) {

    int position = 1;
    char character;

    while(character = getchar()) {

        // (character >= 'a' && character <= 'z') || (character >= 'A' && character <= 'Z');
        // if you prefer
        if (isalpha(character)) {

            // checks capitalitzation of input, if output is not a letter it loops
            // the alphabet so its back into a letter
            if (isupper(character)){
                character = (((character + position - 'A') % 26) + 'A');
            }
            else if (islower(character)){
                character = (((character + position - 'a') % 26) + 'a');
            }
        }
        else if (character == '\n') {

            printf("\n");
            return 0;
        }
        // print end result
        printf("%c", (character));
        position++;

    }   

}