var n,k,i,j,t,t2,ans,sum:longint;
a:array[-500..500,-500..800]of longint;
s:array[-500..500,-500..800]of longint;
functionmax(x,y:longint):longint;
beginif x>y thenexit(x) elseexit(y);
end;
functionmin(x,y:longint):longint;
beginif x<y thenexit(x) elseexit(y);
end;
begin
readln(n,k);
for i:=1to n dobeginfor j:=1to n dobeginread(a[i,j]);
s[i,j]:=s[i,j-1]+a[i,j];
end;
for j:=n+1to n+n do s[i,j]:=s[i,j-1];
end;
if k>=n thenbeginfor i:=1to n do ans:=ans+s[i,n];
writeln(ans);
exit;
end;
for i:=1to n dofor j:=1to n dobegin
sum:=0;
t2:=0;
if i-k<1then t2:=1-(i-k);
for t:=max(i-k,1) to i dobegin
inc(t2);
sum:=sum+s[t,j+t2-1]-s[t,j-t2];
end;
for t:=i+1to min(i+k,n) dobegin
dec(t2);
sum:=sum+s[t,j+t2-1]-s[t,j-t2];
end;
if sum>ans then ans:=sum;
end;
writeln(ans);
end.