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;
const int N = 110000;
const int MOD = 1000000007;
int n, p[N], nr, cs[N], cd[N], aint[4 * N], rez;
vector<int> v[N], c[N], x[N];
bool ver[N];
inline int mo(int nr) { return (nr % MOD + MOD) % MOD; }
int rad(int nod) {
  if (!p[nod]) return nod;
  return p[nod] = rad(p[nod]);
}
void dfs(int nod) {
  ver[nod] = 1;
  cs[nod] = ++nr;
  for (vector<int>::iterator it = v[nod].begin(); it != v[nod].end(); ++it)
    if (!ver[*it]) dfs(*it);
  cd[nod] = nr;
}
void update(int nod, int pozx, int pozy, int poz1, int poz2, int val) {
  if (pozx >= poz1 && poz2 >= pozy) {
    aint[nod] = mo(aint[nod] + val);
    return;
  }
  int mid = (pozx + pozy) / 2;
  if (mid >= poz1) update(2 * nod, pozx, mid, poz1, poz2, val);
  if (mid < poz2) update(2 * nod + 1, mid + 1, pozy, poz1, poz2, val);
}
int query(int nod, int pozx, int pozy, int poz) {
  if (pozx == pozy) return aint[nod];
  int s = 0, mid = (pozx + pozy) / 2;
  if (mid >= poz)
    s = query(2 * nod, pozx, mid, poz);
  else
    s = query(2 * nod + 1, mid + 1, pozy, poz);
  return mo(s + aint[nod]);
}
int main() {
  int i, j, t, tt;
  cin >> n;
  for (i = 1; i <= n; ++i) {
    cin >> nr;
    for (j = 1; j <= nr; ++j) {
      cin >> t >> tt;
      tt = mo(tt);
      c[i].push_back(t);
      x[i].push_back(tt);
      int r1 = rad(t);
      v[i].push_back(r1);
      p[r1] = i;
    }
  }
  nr = 0;
  for (i = 1; i <= n; ++i)
    if (!ver[i]) dfs(rad(i));
  for (i = 1; i <= n; ++i) {
    for (j = 0; j < c[i].size(); ++j) {
      t = mo(x[i][j] + query(1, 1, n, cs[c[i][j]]));
      rez = mo(rez + t);
      update(1, 1, n, cs[v[i][j]], cd[v[i][j]], t);
    }
  }
  cout << rez;
  return 0;
}