var f,w,d:array[1..100000] of longint;
n,i,j:longint;s:int64;

function lca(a,b:longint):longint;
var i:longint;
begin
 if a=b then exit(a);
 if d[a]>d[b] then
   begin
    for i:=1 to d[a]-d[b] do
	 a:=f[a];
   end;
 if d[b]>d[a] then
    begin
	for i:=1 to d[b]-d[a] do
	 b:=f[b];
    end;
 if a=b then exit(a);
 exit(lca(f[a],f[b]));
end;
begin
assign(input,'asm_algo.in');
reset(input);
assign(output,'asm_algo.out');
rewrite(output);
 readln(n,w[1]);
 for i:=2 to n do
   readln(f[i],w[i]);
 f[1]:=1;
 d[1]:=1;
 for i:=1 to n-1 do
 for j:=2 to n do
   if f[j]=i then d[j]:=d[i]+1;
 s:=0;
 for i:=1 to n do
  for j:=1 to n do
   begin
    s:=s+w[i]*w[j]*w[lca(i,j)];
    if s>1000000007 then s:=s mod 1000000007;
   end;
 writeln(s);
close(input);
close(output);
end.