var
p,i,j,k,ans:longint;
d1,d2:array[1..1000]of integer;
color:array[1..1000]of boolean;

procedure check(a,b:longint);
var x,y:longint;
begin
if (d1[a]=0)and(d2[a]=0) then if b+1>ans then ans:=b+1;
color[a]:=true;

if d1[a]>0 then check(d1[a],b+1);
if d2[a]>0 then check(d2[a],b+1);
color[a]:=false;
end;


begin
assign(input,'stroll.in');reset(input);
assign(output,'stroll.out');rewrite(output);

ans:=0;
read(p);
for i:=1 to p-1 do
begin
read(k);
read(d1[k],d2[k]);
end;
fillchar(color,sizeof(color),false);
check(1,0);
write(ans);
close(input);close(output);
end.