---

//1
var fin,fout:text;
i,sum,x:real;
begin
  assign(fin,'C:\in.txt');
  assign(fout,'C:\out.txt');
  Reset(fin);
  while not eof(fin) do begin
    readln(fin,x);
    sum:=sum+x;
    i:=i+1;
  end;
  close(fin);
  x:=sum/i;
  Rewrite(fout);
  write(fout,x);
  close(fout);
end.

//2
var fin,fout:text;
max,min,x:integer;
begin
  assign(fin,'C:\in.txt');
  assign(fout,'C:\out.txt');
  Reset(fin);
  min:=100;
  while not eof(fin) do begin 
    read(fin,x);
    if (x>0) and (x mod 2=0) then begin
      if x>max then max:=x;
      if x<min then min:=x;
    end;
  end;
  close(fin);
  Rewrite(fout);
  if (min>max) then write(fout,'Ошибка')
  else write(fout,'Максимальное: ',max,' Минимальное: ',min);
  close(fout);
end.

//3
var fin,fout:text;
d,x,i,y:integer;
begin
  assign(fin,'C:\in.txt');
  assign(fout,'C:\out.txt');
  reset(fin);
  while not eof(fin) do begin
    readln(fin, x);
    if (i=0) or (x=y) then i:=i+1
    else i:=1;
    if (i>d) then d:=i;
    y:=x;
  end;
  close(fin);
  rewrite(fout);
  writeln(fout, 'Самая длинная цепочка: ', d);
  close(fout);
end.