qbmax

Program QBMAX;
const
        FINP='';
var
	A:array [0..101,0..101] of shortint;
	F:array [0..101,0..101] of integer;
	m,n,i,j:byte;
	res:integer;
        fil:text;
function max(q,w,e:shortint):shortint;
begin
max:=q;
if max<w then max:=w;
if Max<e then max:=e;
end;
procedure init;
begin
for i:=0 to 101 do
	for j:=0 to 101 do
		A[i,j]:=-101;
end;
procedure result;
begin
res:=F[1,n];
for I:=1 to m do
		if res<F[i,n] then res:=F[i,n];
end;

procedure optimize;
begin
	for i:=1 to m do
		F[i,1]:=A[i,1];

        for j:=2 to n do
        	for i:=1 to m do
			begin
				F[i,j]:=max(F[i+1,j-1],F[i-1,j-1],F[i,J-1])+A[i,j];
			end;
end;
begin
        assign(fil,FINP);
        reset(Fil);
        readln(fil,m,n);
	init;

	for i:=1 to m do
                begin
				for j:=1 to n do
				read(fil,A[i,j]);
				readln(fil);
                end;
	optimize;
	result;
	writeln(res);
end.