uses crt;
const fi='sum.inp';
fo='sum.out';
var f1,f2:text;
a:array[1..250]of integer;
n,i,t,dem:integer;
tbc:real;
begin
clrscr;
assign(f1,fi); reset(f1);
assign(f2,fo); rewrite(f2);
readln(f1,n);
for i:=1 to n do
read(f1,a[i]);
{----------------xu-ly--------------------}
t:=0;
dem:=0;
for i:=1 to n do
if (a[i]>0) and (a[i] mod 2=0) then
begin
inc(dem);
t:=t+a[i];
end;
tbc:=t/dem;
writeln(f2,tbc:4:2);
close(f1);
close(f2);
readln;
end.