const n=3;
var
a:array [1..n,1..n] of integer;
i,j,c:integer;
sum:real;
begin
for i:=1 to n do begin
 for j:=1 to n do begin
 read(a[i,j]);
 end;
 readln;
end;
for i:=1 to n do
 for j:=1 to n do
 if (a[i,j]<0) then begin sum:=sum+a[i,j]; inc(c); end;
 writeln(sum/c);
 end.