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;
template <class T>
void pv(T a, T b) {
  for (T i = a; i != b; ++i) cout << *i << " ";
  cout << endl;
}
namespace H {
const int maxv = 1e6, maxe = 1e6, mod = 1e9 + 7;
int to[maxe], ant[maxe], m;
int adj[maxv], n;
vector<vector<int> > path;
int parent[maxv];
int path_id[maxv], path_index[maxv];
int subtree[maxv];
int niv[maxv];
int in[maxv], out[maxv], tempo;
int top_sort[maxv], pos, bla;
inline void init() { memset(adj, -1, sizeof adj), n = m = 0; }
inline void add(int u, int v) {
  to[m] = v, ant[m] = adj[u], adj[u] = m++;
  to[m] = u, ant[m] = adj[v], adj[v] = m++;
  n = max(n, max(++u, ++v));
}
void dfs(int no = 0, int pai = -1, int nivel = 0) {
  in[no] = tempo++;
  subtree[no] = 1;
  niv[no] = nivel;
  parent[no] = pai;
  for (int i = adj[no]; i >= 0; i = ant[i]) {
    int prox = to[i];
    if (prox == pai) continue;
    dfs(prox, no, nivel + 1);
    subtree[no] += subtree[prox];
  }
  out[no] = tempo++;
  top_sort[pos++] = no;
}
vector<bool> parent_edge_processed;
vector<vector<int> > bits;
void p_heavy_light() {
  path.clear();
  parent_edge_processed = vector<bool>(n, false);
  bla = 0;
}
void heavy_light(int root) {
  pos = 0, dfs(root);
  parent_edge_processed[root] = true;
  for (int i = 0; i < pos; i++) {
    int first = top_sort[i];
    if (parent_edge_processed[first]) continue;
    vector<int> this_path;
    this_path.push_back(first);
    for (;;) {
      int is_heavy = (2 * subtree[first] >= subtree[parent[first]]);
      parent_edge_processed[first] = true;
      first = parent[first];
      this_path.push_back(first);
      if (!is_heavy || parent_edge_processed[first]) break;
    }
    path.push_back(this_path);
    bits.push_back(vector<int>(this_path.size() + 3, 0));
  }
  path_id[root] = -1;
  for (int i = path.size() - 1; i >= bla; i--)
    for (int j = path[i].size() - 2; j >= 0; j--)
      path_id[path[i][j]] = i, path_index[path[i][j]] = j;
  bla = path.size();
}
inline bool is_ancestor(int first, int second) {
  return in[second] <= in[first] && out[first] <= out[second];
}
int lca(int u, int v) {
  for (;;) {
    if (is_ancestor(v, u))
      return u;
    else if (is_ancestor(u, v))
      return v;
    int fu = path[path_id[u]].back(), fv = path[path_id[v]].back();
    if (niv[fu] >= niv[fv])
      u = fu;
    else
      v = fv;
  }
}
long long qbit(int idx, int first) {
  long long R = 0;
  while (first) {
    R = (R + bits[idx][first]) % mod;
    first -= first & -first;
  }
  return R;
}
void ubit(int idx, int first, int second) {
  while (first < bits[idx].size()) {
    bits[idx][first] = (bits[idx][first] + second) % mod;
    first += first & -first;
  }
}
int query(int node, int root) {
  long long R = 0;
  for (; node != root;) {
    if (path_id[node] == path_id[root]) {
      R = (R + qbit(path_id[node], path_index[root] + 1)) % mod;
      R = (R + mod - qbit(path_id[node], path_index[node])) % mod;
      node = root;
    } else {
      R = (R + qbit(path_id[node], path[path_id[node]].size())) % mod;
      R = (R + mod - qbit(path_id[node], path_index[node])) % mod;
      node = path[path_id[node]].back();
    }
  }
  return R;
}
void update(int node, int root, int first) {
  ubit(path_id[node], path_index[node] + 1, first);
}
void debug() {
  for (int i = 0; i < bits.size(); ++i) {
    cerr << "qbit(i, bits[i].size() - 1)"
         << " == " << qbit(i, bits[i].size() - 1) << endl;
  }
}
};  // namespace H
const int mod = 1e9 + 7, maxn = 1e6 + 10;
int n;
int k[maxn], v[maxn], first[maxn];
int root[maxn];
int find(int first) {
  if (first != root[first]) root[first] = find(root[first]);
  return root[first];
}
int main() {
  cin.sync_with_stdio(false);
  cin >> n;
  int last = 0;
  H::init();
  for (int i = 0; i < n; ++i) {
    root[i] = i;
    cin >> k[i];
    for (int j = 0; j < k[i]; ++j) {
      cin >> v[last] >> first[last];
      first[last] %= mod;
      first[last] += mod;
      first[last] %= mod;
      v[last]--;
      int w = find(v[last]);
      root[w] = i;
      H::add(w, i);
      last++;
    }
  }
  H::p_heavy_light();
  for (int i = 0; i < n; ++i)
    if (find(i) == i) H::heavy_light(i);
  last = 0;
  int ans = 0;
  for (int i = 0; i < n; ++i) {
    root[i] = i;
    for (int j = 0; j < k[i]; ++j) {
      int w = v[last], fw = find(w);
      root[fw] = i;
      int R = H::query(w, i);
      R = (R + first[last]) % mod;
      last++;
      ans = (ans + R) % mod;
      H::update(fw, i, R);
    }
  }
  cout << ans << endl;
  return 0;
}