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>
std::pair<int, int> mp(int a, int b) { return std::make_pair(a, b); }
struct dat {
  int d, a, b;
  dat() { d = a = b = 0; }
  dat(int _d, int _a, int _b) { d = _d, a = _a, b = _b; }
};
int n;
int deg[100010];
std::vector<dat> edg[100010];
int fat[100010];
int T, in[100010], out[100010], vis[100010];
int zkw[(1 << 18) * 2];
int fa(int now) {
  if (fat[now] == now) return now;
  return fat[now] = fa(fat[now]);
}
void dfs(int now, int fa) {
  ++T;
  in[now] = T, vis[now] = 1;
  for (int i = 0; i < edg[now].size(); ++i) {
    int ne = edg[now][i].b;
    if (ne == fa || vis[ne] == 1) continue;
    dfs(ne, now);
  }
  ++T;
  out[now] = T;
}
void update(int le, int ri, int val) {
  le = le + (1 << 18) - 1, ri = ri + (1 << 18) + 1;
  for (; le ^ ri ^ 1; le >>= 1, ri >>= 1) {
    if (~le & 1) {
      int p = le ^ 1;
      zkw[p] += val;
      if (zkw[p] >= 1000000007) zkw[p] -= 1000000007;
    }
    if (ri & 1) {
      int p = ri ^ 1;
      zkw[p] += val;
      if (zkw[p] >= 1000000007) zkw[p] -= 1000000007;
    }
  }
}
int query(int now) {
  int r = 0;
  for (now += (1 << 18); now > 0; now >>= 1) {
    r += zkw[now];
    if (r >= 1000000007) r -= 1000000007;
  }
  return r;
}
int main(void) {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) fat[i] = i;
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &deg[i]);
    for (int j = 0, a, b; j < deg[i]; ++j) {
      scanf("%d%d", &a, &b);
      if (b < 0) b += 1000000007;
      edg[i].push_back(dat(b, a, fa(a)));
      int t = fa(a);
      fat[t] = i;
    }
  }
  for (int i = 1; i <= n; ++i) {
    if (vis[i] == 0 && fat[i] == i) dfs(i, 0);
  }
  int ans = 0;
  for (int i = 1; i <= n; ++i) {
    for (int j = 0; j < edg[i].size(); ++j) {
      int ne = edg[i][j].a, nef = edg[i][j].b;
      int t = query(in[ne]) + edg[i][j].d;
      if (t >= 1000000007) t -= 1000000007;
      ans += t;
      if (ans >= 1000000007) ans -= 1000000007;
      update(in[nef], out[nef], t);
    }
  }
  printf("%d\n", ans);
  return 0;
}