Uses crt;
  Var
    a:array[1..10,1..10] of integer;
    i,j,s,k,n:integer;
begin
read(k);
read(n);
for i:=1 to n do begin
for j:=1 to n do begin
read(a[i,j]);
if (i-j=k) or (j-i=k) then s:=s+a[i,j];
end;
end;
write('s=',s);
end.