var i,n:integer;
begin
write('n = ');readln(n);
i:=2;
while n mod i <> 0 do i:=i+1;
if i = n then write(n,' la so nguyen to')
else write(n,' khong la so nguyen to');
readln
end.
Uses crt;
var i,n,p: integer;
begin clrscr;
readln(n);
for i:=1 to n do if(n mod i=0) then p:=p+1;
if(p=2) then writeln(n,' la so nguyen to')
else writeln(n,' khong phai la so nguyen to');
readln;
end.