uses crt;
var a,b,s:integer;
begin
clrscr;
write('Nhap so A co 2 chu so: ');readln (a);
if (a>9) and (a<100) then begin
s:=0;
while a<>0 do
begin
b:=a mod 10;
a:=a div 10;
s:=s+b;
end;
write('Tong 2 chu so A la: ',s); end else write('So A nhap vao khong thoa man');
readln;
end.