program x;
var s,N,a,i,k,g:integer;
begin
k:=0;
s:=0;
g:=0;
readln(a);
while a<> 0 do
begin
IF ( a mod 8=0) then
begin
g:=g+1;
s:=a+s;
k:=k+1;
end;
readln(a);
end;
IF k>0 then writeln(s/k) else writeln('NO');
end.