OPTIONS NODATE NONUMBER LS=72;

LIBNAME C 'C:\COURSES\SASSEM';

DATA in;
  DO x1 = 'A' , 'B';
  DO x2 = 1 TO 2;
  DO rep = 1 TO 2;
     INPUT y @@; OUTPUT;
  END; END; END;
CARDS;
1 2 3 4 6 8 5 0 
;
PROC SORT DATA=in; BY x2 x1;

PROC PRINT DATA=in;
     ID y;

DATA C.prob1; SET in;

DATA prob1; SET C.prob1;

PROC CONTENTS DATA=prob1;
RUN;