各位大虾，帮忙查错

提示（26，4）有错：
program sdf;
var
a:array[1..50]of integer;
c,b,i:integer;
begin
i:=0;
write('c=');
readln(c);
repeat
inc(i);
a[i]:=c mod 16;
c:=c div 16;
until c<16;
b:=i;
case c of
10 : write('A');
11 : write('B');
12 : write('C');
13 : write('D');
14 : write('E');
15 : write('F');
else write(c);
for i:= b downto 1 do
write(a[i]);
readln
end.