Problem: An oriented weighted forest is an acyclic weighted digraph in which from each vertex at most one edge goes.

The root of vertex v of an oriented weighted forest is a vertex from which no edge goes and which can be reached from vertex v moving along the edges of the weighted oriented forest. We denote the root of vertex v as root(v).

The depth of vertex v is the sum of weights of paths passing from the vertex v to its root. Let's denote the depth of the vertex v as depth(v).

Let's consider the process of constructing a weighted directed forest. Initially, the forest does not contain vertices. Vertices are added sequentially one by one. Overall, there are n performed operations of adding. The i-th (i > 0) adding operation is described by a set of numbers (k, v1, x1, v2, x2, ... , vk, xk) and means that we should add vertex number i and k edges to the graph: an edge from vertex root(v1) to vertex i with weight depth(v1) + x1, an edge from vertex root(v2) to vertex i with weight depth(v2) + x2 and so on. If k = 0, then only vertex i is added to the graph, there are no added edges.

Your task is like this: given the operations of adding vertices, calculate the sum of the weights of all edges of the forest, resulting after the application of all defined operations, modulo 1000000007 (109 + 7).

Input

The first line contains a single integer n (1 ≤ n ≤ 105) — the number of operations of adding a vertex.

Next n lines contain descriptions of the operations, the i-th line contains the description of the operation of adding the i-th vertex in the following format: the first number of a line is an integer k (0 ≤ k ≤ i - 1), then follow 2k space-separated integers: v1, x1, v2, x2, ... , vk, xk (1 ≤ vj ≤ i - 1, |xj| ≤ 109). 

The operations are given in the order, in which they should be applied to the graph. It is guaranteed that sum k of all operations does not exceed 105, also that applying operations of adding vertexes does not result in loops and multiple edges. 

Output

Print a single number — the sum of weights of all edges of the resulting graph modulo 1000000007 (109 + 7).

Examples

Input

6
0
0
1 2 1
2 1 5 2 2
1 1 2
1 3 4


Output

30


Input

5
0
1 1 5
0
0
2 3 1 4 3


Output

9

Note

Conside the first sample:

  1. Vertex 1 is added. k = 0, thus no edges are added.
  2. Vertex 2 is added. k = 0, thus no edges are added.
  3. Vertex 3 is added. k = 1. v1 = 2, x1 = 1. Edge from vertex root(2) = 2 to vertex 3 with weight depth(2) + x1 = 0 + 1 = 1 is added. 
  4. Vertex 4 is added. k = 2. v1 = 1, x1 = 5. Edge from vertex root(1) = 1 to vertex 4 with weight depth(1) + x1 = 0 + 5 = 5 is added. v2 = 2, x2 = 2. Edge from vertex root(2) = 3 to vertex 4 with weight depth(2) + x1 = 1 + 2 = 3 is added.
  5. Vertex 5 is added. k = 1. v1 = 1, x1 = 2. Edge from vertex root(1) = 4 to vertex 5 with weight depth(1) + x1 = 5 + 2 = 7 is added.
  6. Vertex 6 is added. k = 1. v1 = 3, x1 = 4. Edge from vertex root(3) = 5 to vertex 6 with weight depth(3) + x1 = 10 + 4 = 14 is added.



The resulting graph is shown on the pictore below: <image>

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
void run();
int main() {
  ;
  ios::sync_with_stdio(false);
  run();
}
long long const l = 100000;
long long const mod = 1000000007;
struct LinkCut {
  LinkCut *p, *l, *r;
  long long weight;
  long long sum;
  inline LinkCut(LinkCut* p = nullptr) : p(p) { l = r = nullptr; }
  inline bool root() { return not p or p->l != this and p->r != this; }
  inline void push() { sum = weight + (l ? l->sum : 0) + (r ? r->sum : 0); }
  inline void increase(long long by) {
    splay();
    (weight += by) %= mod;
    push();
  }
  inline void rot(LinkCut* LinkCut::*a, LinkCut* LinkCut::*b) {
    if (not root()) (p->l == this ? p->l : p->r) = (this->*a);
    (this->*a)->p = p, p = (this->*a);
    (this->*a) = (p->*b), (p->*b) = this;
    if (this->*a) (this->*a)->p = this;
    if (l) l->push();
    if (r) r->push();
    push();
  }
  inline void rotate() {
    if (p->l == this)
      p->rot(&LinkCut::l, &LinkCut::r);
    else
      p->rot(&LinkCut::r, &LinkCut::l);
  }
  inline void splay() {
    push();
    while (not root()) {
      if (not p->root()) p->p->push();
      p->push();
      push();
      if (not p->root())
        ((p->l == this) == (p->p->l == p) ? p : this)->rotate();
      rotate();
    }
    push();
  }
  inline void link(LinkCut* x) {
    splay();
    p = x;
    p->splay();
  }
  inline void expose() {
    for (LinkCut *i = this, *j = nullptr; i; j = i, i = i->p) {
      i->splay();
      i->l = j;
      i->push();
    }
    splay();
  }
  inline long long depth() {
    splay();
    return sum;
  }
  inline LinkCut* findroot() {
    expose();
    LinkCut* x = this;
    while (x->r) x = x->r, x->push();
    return x;
  }
};
LinkCut tree[l];
long long w[l];
void run() {
  long long res = 0;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int k;
    cin >> k;
    for (int j = 0; j < k; j++) {
      long long v, x;
      cin >> x >> v;
      --x;
      while (v < 0) v += mod;
      long long plus = tree[x].findroot()->depth();
      long long y = tree[x].findroot() - tree;
      tree[y].link(tree + i);
      tree[y].increase(v + plus);
      (res += v + plus) %= mod;
    }
  }
  cout << res << endl;
}