program r7_38;
uses crt;
const n=20;
var a,b:array[1..n] of integer;
      i,j,r,r1,d:integer;
      h:boolean;
function Simple(x:word):boolean;
 var d:word;
  begin
   d:=2;
  while(x mod d <>0) and(d<=sqrt(x))do
  d:=d+1;
  simple:=(d>sqrt(x));
 end;
Begin
clrscr;
randomize;
for i:=1 to n do begin
 a[i]:=random(50);
 write(a[i]:4);
end;writeln;
h:=false;
for i:=1 to n-1 do
for j:=i+1 to n do
  if ((abs(a[i]-a[j])=2) and simple(a[i]) and simple(a[j]))then
   begin
    h:=true;
    r:=a[i];
    r1:=a[j];
   end;
  if h=true then writeln('est:',r:4,' ',r1:4)
  else writeln('net');
END.