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.

输入：
5
2
-1 4
2 -1 -2
-1 6 4 0
3 2 -1 5 8
输出：14