program nguyento;
uses crt;
var n,t:integer;
function ktnt(k:integer):boolean;
var l:integer;
begin
ktnt:=false;
if k<2 then exit;
for i:=2 to trunc(sqrt(k)) do
if k mod l=0 then exit;
ktnt:=true;
end;
BEGIN
clrscr;
write('Nhap vao t = '); readln(t);
if t<=2 then writeln('Khong co so nguyen to nho hon')
else begin
n:=t-1;
while ktnt(n)=false then n:=n-1;
writeln('d1: ',n);
end;
n:=t+1;
while ktnt(n)=false then n:=n+1;
writeln('d2: ',n);
readln;
end.