USES CRT;
Var n: byte;
Function SNT(X: longint): boolean;
var nt: boolean;
k: longint;
begin
nt:=x>1;
for k:=2 to trunc(sqrt(x)) do
if x mod k=0 then
begin
nt:=false;
break
end;
SNT:=nt;
end;
begin
write('Nhap so N='); readln(n);
if SNT(n)=true then writeln(n ,' la so nguyen to.')
else writeln(n,' khong phai so nguyen to.');
readln;
end.