#include /* io.c */ CELL *get_a_row(int); int put_a_row(int, CELL *); int read_row(int, char *, int, int); int write_row(int, char *, int, int); int open_file(char *); int close_file(char *); int map_size(int *, int *, int *); /* thin_lines.c */ int thin_lines(int); char encode_neighbours(CELL *, CELL *, CELL *, int, int);