var
c: array[1..30] of integer;
i,n,k:integer;
begin
n:=0;
k:=0;
for i:=1 to 30 do
readln(c[i]);

for i:=1 to 30 do begin
if c[i]<0 then begin
n:=n+1;
k:=k+c[i];
end;
end;
writeln('srednee=', k/n )
end.