var a,s,k: integer;
begin
readln(a);
s:=0;
k:=0;
while(a<>0) do
if a>0 then begin
s:=s+a;
k:=k+1;
end;
write(s/k);
end.
var a,s,k: integer;
begin
readln(a);
s:=0;
k:=0;
while(a<>0) do
begin
if a>0 then begin
s:=s+a;
k:=k+1;
end;
readln(a);
end;
write(s/k);
end.