#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<strings.h>

typedef struct amino{
char seq;
struct amino *before;
struct amino *after;        
}AMINO;

int main (void)
{FILE *data, *output, *output1;
 data = fopen ("Sample.txt", "r");
 output = fopen ("output_sample1.txt","w");
 output1 = fopen ("output_sample2.txt","w");
 char input[100] = {};
 AMINO *ptr;
 AMINO *start; 
 AMINO *start1;
 AMINO *next;
 AMINO *pop;
 AMINO *pop1;
 
 while (fgets(input,100,data)!= NULL)
       { if (strstr(input, "SQ   SEQUENCE   " ) != NULL)
            { fprintf (output, "=================================\n");
              start = malloc (sizeof (AMINO));
              start1 = start;
              start->before = NULL;
              start->after = NULL;
                  while ( (start->seq = fgetc (data)) != '/')
                      { fprintf (output, "%c", start->seq);
                          if (start->seq == ' ' || start->seq == '\n')
                              {   fprintf(output,"_");
                                  (AMINO*)pop = (AMINO*)start;
                                  (AMINO*)pop1 = (AMINO*)start->before;
                                   start = (AMINO*)pop1;
                                   start->after = NULL;
                                   free(pop);
                              }
                        next = malloc (sizeof(AMINO));
                        start->after = next;                       
                        next->before = start;
                        start = next;
                        start->after = NULL;
                      }
               ptr = start1;
               while(ptr->after != NULL)
                   {fprintf (output1, "%c", ptr->seq);
                    ptr = ptr->after;
                    }
             fprintf(output1, "\n==============================\n");
             free (start1);
           }
       }
fclose (data);
fclose (output);
fclose (output1);
return EXIT_SUCCESS; 
}