uses crt;
var i,n,kt:integer;
begin
clrscr;
readln(n);
kt:=0;
for i=2 to trunc(sqrt(n)) do
if n mod i=0 then kt:=1;
if (kt=0) and (n>1) then write('phai')
else write('Khong phai');
readln;
end.
Var i,n,souoc:integer;
Begin
While n <= 1 do
Begin
Write('Nhap n = ');readln(n);
End;
For i:=1 to n do
If n mod i = 0 then souoc:=souoc+1;
If souoc = 2 then write(n,' la so nguyen to')
Else write(n,' khong la so nguyen to');
Readln;
End.