var n, i, j : integer; ...

var
  n, i, j : integer;
  a : array[1．．100, 1．．100] of integer;
function solve(x, y : integer) : integer;
var
  u, v : integer;
begin
  if x = n then
  begin
    solve := a[x, y];
    exit;
  end;
  u := solve(x + 1, y);
  v := solve(x + 1, y + 1);
  if u > v then solve := a[x, y] + u
  else solve := a[x, y] + v;
end;
begin
  read(n);
  for i:= 1 to n do
    for j:=1 to i do read(a[i, j]);
  writeln(solve(1, 1));
end