data test;
input class $ year name $ score;
datalines;
a 2011 jan 45
b 2011 mike 43
b 2011 jack 59
b 2011 kate 46
c 2011 marry 46
;
run;
proc format;
value grade 1="A"
2="B"
3="C";
run;
proc sort data=test;by class descending score;run;
data result;
set test;
by class descending score;
if first.class then grade=1;
else grade+1;
grade1=put(grade,grade.);
run;