program bai_giai;
uses crt;
var f,g:text;
n,i:integer;
function ktnt(k:integer):boolean;
var r:integer;
begin
ktnt:=false;
if k<2 then exit;
for r:=2 to trunc(sqrt(k)) do
if k mod r=0 then exit;
ktnt:=true;
end;
BEGIN
clrscr;
Assign(f,'NGUYENTO.INP'); reset(f);
Assign(g,'NGUYENTO.OUT'); rewrite(g);
readln(f,n);
if n<=3 then writeln(g,'Khong co uoc nao la so nguyen to')
else
for i:=n div 2 downto 2 do
if (n mod i=0) and (ktnt(i)) then
begin
writeln(g,'Uoc so nguyen to lon nhat la: ',i);
break;
end;
i:=n+1;
while ktnt(i)=false do i:=i+1;
writeln(g,'So nguyen to nho nhat lon hon ',n,' la: ',i);
if n<=2 then writeln(g,'Khong co so nao nho hon ',n,' la so nguyen to')
else
begin
i:=n-1;
while ktnt(i)=false do i:=i-1;
writeln(g,'So nguyen to lon nhat nho hon ',n,' la: ',i);
end;
readln;
end.
