extern size_t fread(void *buf, size_t size, size_t n, FILE *fp);
extern size_t fwrite(const void *buf, size_t size, size_t n, FILE *fp);
extern int fgetc(FILE *fp);
extern size_t fread(void *buf, size_t size, size_t n, FILE *fp);
extern size_t fwrite(const void *buf, size_t size, size_t n, FILE *fp);
extern int fgetc(FILE *fp);