Program Tin_hoc;
Uses crt;
Var i,n: longint;
res: boolean;
Begin
Writeln('Nhap n: '); Readln(n);
res:=true;
For i:=2 to trunc(sqrt(n)) do
If n mod i = 0 then res:=false;
If res=false then write(n,' khong phai la so nguyen to')
else write(n,' la so nguyen to');
Readln
End.