*dùng repeat...until
program khac_0;
uses crt;
var n:integer;
begin
clrscr;
repeat
write('Nhap so: '); readln(n);
until n<>0;
readln;
end.
*dùng while...do
program khac_0;
uses crt;
var n:integer;
begin
clrscr;
write('Nhap so: '); readln(n);
while n=0 do
begin
write('Nhap so: '); readln(n);
end;
readln;
end.