program discesa;
Uses Math;
var A,i,j, ans:integer;
    tab, DP :array[1..10,1..10] of integer;
begin
    (*assign(input,  'input.txt');  reset(input);
    assign(output, 'output.txt'); rewrite(output);*)
	readln(A);
	for i:=1 to A do 
	               begin
	                   for j:=1 to i do read(tab[i,j]);
	                   readln; 
	               end;
    for i:=1 to A do
                for j:=1 to A do DP[i,j]:=0;
    DP[1,1]:=tab[1,1];  DP[2,1]:=DP[1,1]+tab[2,1]; DP[2,2]:=DP[1,1]+tab[2,2];         
    for i:=2 to A do DP[i,1]:=DP[i-1,1]+ tab[i,1];           
	for i:=3 to A  do
	         for j:=2 to i do
	                DP[i,j]:=max(DP[i-1,j-1]+tab[i,j],DP[i-1,j]+tab[i,j]);
	ans:=0;
	for i:=1 to A do if DP[A,i]>ans then ans:=DP[A,i] ;
	writeln(ans);
end.
 

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