var n,i,m,k,sum,j:integer;
    a:array[1..100, 1..100]of integer;
begin
    readln(n, m);
    for i:=1 to n do
       for j:=1 to m do
         read(a[i,j]);
    k:=0;
    sum:=0;
    for i:=1 to n do
       if (a[i,i] mod 2 = 0) then begin
          k:=k+1;
          sum:=sum+a[i,i];
       end;
    if (k>0) then
       writeln(sum/k)
    else
       writeln('cannot divide by zero');
end.