code pascal:

program baitap;

uses crt;

var n,i:longint;

function snt(x:longint):boolean;

vả j:Longint;

begin

snt:=true;

if x < 2 then snt:=false;

if x = 2 then snt:=true;

if x > 2 then

for j:=2 to trunc(sqrt(x)) do

if x mod j=0 then snt:=false;

end;

begin

clrscr;

write('nhap n= ');

read(n);

if snt(n) then write('So do la so nguyen to')

else write('So do la hop so');

readln;

readln;

end.

var
i,n,j:longint;
function nt(x:longint):boolean;
begin
nt:=true;
if x<2 then nt:=false;
if x=2 then nt:=true;
if x>2 then
for j:=2 to trunc(sqrt(x)) do
if x mod j=0 then nt:=false;
end;
begin
write('nhap n=');
read(n);
if n=0 then
begin
write('ko la nt,ko la hop so');
exit;
end;
if n=1 then
begin
write('ko la nt,ko la hop so');
exit;
end;
if nt(n) then write('so do la nguyen to');
if not nt(n)  then
write('so do la hop so');
end.