#include <stdio.h>

typedef struct {
	int restart, g, b;
	char ch;
} Fmt;

void format( Fmt * f ) {
	static void * states[] = {&&s0, &&s1};
	goto *states[f->restart];
  s0: f->restart = 1;
	for ( ;; ) {
		for ( f->g = 0; f->g < 5; f->g += 1 ) {			// groups
			for ( f->b = 0; f->b < 4; f->b += 1 ) {		// blocks
				return;
			  s1: if ( f->ch == '\0' ) goto fini;		// EOF ?
				while ( f->ch == '\n' ) return;			// ignore
//				printf( "%c", f->ch );					// print character
			}
//			printf( " " );								// block separator
		}
//		printf( "\n" );									// group separator
	}
  fini:;
//	if ( f->g != 0 || f->b != 0 ) printf( "\n" );
}

int main() {
	Fmt fmt = { 0 };
	format( &fmt );										// prime
	fmt.ch = 'a';
	for ( long int i = 0; i < 1000000000; i += 1 ) {
//		scanf( "%c", &fmt.ch );							// direct read into communication variable
//	  if ( feof( stdin ) ) break;
		format( &fmt );
	}
	fmt.ch = '\0';										// sentential (EOF)
	format( &fmt );
}

// Local Variables: //
// tab-width: 4 //
// compile-command: "gcc-8 Format1.c" //
// End: //