var a: array[1..5] of integer;
i,p,s: integer;
begin
for i:=1 to 5 do read(a[i]);
p:=1;
s:=0;
for i:=1 to 5 do begin
p:=p*a[i];
s:=s+a[i];
end;
write('ответ: ',p/(2*s));
end.
