/* Using a pipe to handle interprocess communication: GETP/PUTP
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

#define GET(x) notend=EOF!=(x=getchar())
#define PUT(x) putchar(x)
#define pf(a,b,c,d) {c=b;d=a;}

error(char *s) { fprintf(stderr, "\n cryptop: %s \n", s);}

int piped[2];

#define PUTP(c)	if(write(piped[1], &c, sizeof(c))==-1)error("Write failed")
#define GETP(c)	notend=read(piped[0], &c, sizeof(c))!=-1

main(){
	int a,b,c,d,notend;

	if(pipe(piped)==-1)error("Pipe() failed!");

	if(fork()==0){/*child process starts here*/
		p2();
	}/*end of child*/
	else {/* start of parent(!)*/
		close(piped[0]);
		GET(a);GET(b);

		while( notend ){

			pf(a,b,c,d); 
			PUTP(c); PUTP(d); GET(a); GET(b);

		}
	}/*end of parent*/

}

p2() 
{
	int n,m, notend, c;
	close(piped[1]);
	GETP(c);
	while(notend){ /*line*/

        	for( m=1; notend && m<=10; m++ ){ /*group*/
            		for( n=1; notend && n<=5; n++ ){

               			 PUT(c);
				 GETP(c);

            		}

            		PUT(' ');
        	}

        	PUT('\n');
    	}

    	return(0);
}