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 JAVA):

Solution:
import java.io.*;
import java.math.BigInteger;
import java.util.*;
import java.util.Map.Entry;

public class Main {
	public static void main(String[] args) throws IOException {
		(new Main()).solve();
	}

	public void Main() {
	}

	void solve() throws IOException {
		// BufferedReader in = new BufferedReader(new
		// InputStreamReader(System.in));
		// Scanner in = new Scanner(System.in);
		MyReader in = new MyReader();
		PrintWriter out = new PrintWriter(System.out);
		// Scanner in = new Scanner(new FileReader("input.txt"));
		// PrintWriter out = new PrintWriter("output.txt");
		Map<Integer,Vertex> forest = new HashMap<Integer,Vertex>();
		
		int n = in.nextInt();
		int sum = 0;
		final int MOD = 1000000007;
		
		for (int i = 1; i <= n; i++) {
			int k = in.nextInt();
			Vertex cur = new Vertex();
			for (int j = 0; j < k; j++) {
				ArrayList<Vertex> h = new ArrayList<Vertex>();
				int v = in.nextInt();
				int x  = (in.nextInt() + MOD) % MOD;
				Vertex vv = forest.get(v);
				while (vv.parent != -1) {
					h.add(vv);
					x = (x + vv.depth)%MOD;
					vv = forest.get(vv.parent);					
				}
				vv.parent = i;
				vv.weight = x;
				vv.depth = x;
				//vv.depth = 0;
				h.add(vv);
				for (int ii = h.size() - 2; ii > -1; ii--) {
					Vertex t = h.get(ii);
					t.parent = i;
					t.depth = (t.depth + h.get(ii + 1).depth) % MOD;
				}
				//Vertex v2 = forest.get(v);
				sum = (sum + x) % MOD;
				//vv.depth += x;
			}
			forest.put(i, cur);
		}
		
		out.println(sum);
		
		out.close();
	}

};

class Vertex {
	public int parent = -1;
	public int depth = 0;
	public int weight = 0;
}


class MyReader {
	private BufferedReader in;
	String[] parsed;
	int index = 0;

	public MyReader() {
		in = new BufferedReader(new InputStreamReader(System.in));
	}

	public int nextInt() throws NumberFormatException, IOException {
		if (parsed == null || parsed.length == index) {
			read();
		}
		return Integer.parseInt(parsed[index++]);
	}

	public long nextLong() throws NumberFormatException, IOException {
		if (parsed == null || parsed.length == index) {
			read();
		}
		return Long.parseLong(parsed[index++]);
	}

	public String nextString() throws IOException {
		if (parsed == null || parsed.length == index) {
			read();
		}
		return parsed[index++];
	}

	private void read() throws IOException {
		parsed = in.readLine().split(" ");
		index = 0;
	}

	public String readLine() throws IOException {
		return in.readLine();
	}
};