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;
class Dsu {
  vector<int> par, ss, val;
  int get(int x) { return par[x] == x ? x : par[x] = get(par[x]); }

 public:
  Dsu(int n = 0) : par(n), ss(n, 1), val(n) {
    for (int i = 0; i < n; i++) par[i] = val[i] = i;
  }
  int getVal(int x) { return val[get(x)]; }
  int getSize(int x) { return ss[get(x)]; }
  void mergeTo(int a, int b) {
    a = get(a);
    b = get(b);
    int nv = val[b];
    if (a == b) return;
    if (ss[a] > ss[b]) swap(a, b);
    par[a] = b;
    ss[b] += ss[a];
    val[b] = nv;
  }
};
const int MOD = 1e9 + 7;
void madd(int &a, int b) {
  a += b;
  while (a >= MOD) a -= MOD;
}
int mplus(int a, int b) {
  madd(a, b);
  return a;
}
int n;
vector<vector<int> > chi;
Dsu dsu;
vector<int> pot;
void dfsAddPot(int v, int x) {
  madd(pot[v], x);
  for (int i = 0; i < ((int)(chi[v]).size()); i++) dfsAddPot(chi[v][i], x);
}
void addE(int a, int b, int w) {
  int npar = b, nchi = a;
  int addToBpot = mplus(w, MOD - mplus(pot[b], MOD - pot[a]));
  if (dsu.getSize(a) < dsu.getSize(b))
    swap(a, b), addToBpot = mplus(MOD - addToBpot, 0);
  dfsAddPot(b, addToBpot);
  dsu.mergeTo(nchi, npar);
  chi[npar].push_back(nchi);
}
int main() {
  int n;
  while (scanf("%d", &n) >= 1) {
    chi = vector<vector<int> >(n);
    dsu = Dsu(n);
    pot = vector<int>(n, 0);
    int ans = 0;
    for (int i = 0; i < n; i++) {
      int k;
      scanf("%d", &k);
      for (int i2 = 0; i2 < k; i2++) {
        int v, x;
        scanf("%d%d", &v, &x), v--;
        while (x < 0) x += MOD;
        while (x >= MOD) x -= MOD;
        assert(0 <= v && v < i);
        int root = dsu.getVal(v);
        int nw = mplus(mplus(pot[root], MOD - pot[v]), x);
        madd(ans, nw);
        addE(root, i, nw);
        assert(mplus(pot[i], MOD - pot[root]) == nw);
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}