program zadanie;
uses crt;
var input:file of longint;
   i,n,k,s,f:longint;
   m:real;
Begin
clrscr;
assign(input,'input.dat');
rewrite(input);
writeln('Vvedit kol. chusel');
readln(f);
for i:=1 to f do
 begin
  write('Vvedit chuslo  ');
  readln(n);
  write(input,n);
 end;
close(input);
reset(input);
k:=0;
s:=0;
i:=0;
while not eof(input) {i<=filesize(input)-1} do
begin
  seek(input,i);
  read (input,n);
  if k<5 then
  begin
   s:=s+n;
   inc(k);
  end;
  if k=5 then
  begin
   m:=s/k;
   writeln (m:4:2);
  end;
  if i=filesize(input)-1 then
  begin
   m:=s/k;
   writeln(m:4:2);
  end;
close (input);
end;
end.