#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <fcntl.h>

int main(int argc, char **argv)  {
    if(argc != 1) printf("usage: decrypt filename\n");
    int absolut = 0;
    char ch = 'q';
    int nextpos = 0;
    int in = open(argv[1], O_RDONLY);
    if(in < 0) {
        perror("open"), exit(1);
    }
  
   lseek(in, 0, SEEK_SET);
   absolut =0;
   ch = 'q';
   nextpos =0;   
   while(1) {
        read(in, &nextpos, sizeof(int));
        absolut = nextpos * (sizeof(int) + 1);
        lseek(in, absolut, SEEK_CUR);
        read(in, &ch, sizeof(char));
        lseek(in, -5, SEEK_CUR);
        if (ch == '#') break;
        printf("%c", ch);
   }

   return 0;
}