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:
//package contest_123_div2;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.Writer;
import java.util.HashMap;
import java.util.Map;
/**
 * Date     : Jun 29, 2012
 * Time     : 5:32:53 PM
 * Email    : denys.astanin@gmail.com
 */

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

	int nextInt() throws IOException {
		in.nextToken();
		return (int) in.nval;
	}

	String nextString() throws IOException {
		in.nextToken();
		return (String) in.sval;
	}

	StreamTokenizer in;
	Writer writer;
	Reader reader;
	Map<Integer, Long> size = new HashMap<Integer, Long>();
	Map<Integer, Integer> p    = new HashMap<Integer, Integer>();
	long currentWeight;  
	int find_set(int vertex) {
		int parent = p.get(vertex);
		if (parent == vertex) {
			return vertex;
		}
		int pp = find_set(parent);
		long temp = size.get(vertex);
		size.put(vertex, (size.get(vertex) + currentWeight) % 1000000007L);
		currentWeight += temp;
		p.put(vertex, pp);
		return pp;
	}
	void make_set(int vertex) {
		p.put(vertex, vertex);
		size.put(vertex, 0L);
	}
	long edge = 0;
	int union_sets(int vertex1, int vertex2, int x) {
		currentWeight = 0; 
		int a = find_set(vertex1);
		long aWeight = currentWeight;
		
		currentWeight = 0; 
		int b = find_set(vertex2);
		long bWeight = currentWeight;
		
		if (a == b) {
			return a;
		}
		p.put(a, b);
		edge = aWeight + x;
		size.put(a, (aWeight + x) % 1000000007L);
		return b;
	}
	void run() throws IOException {
		boolean oj = System.getProperty("ONLINE_JUDGE") != null;
		reader = oj ? new InputStreamReader(System.in, "ISO-8859-1")
				: new FileReader("src/contest_123_div2/E.txt");
		writer = new OutputStreamWriter(System.out, "ISO-8859-1");
		in = new StreamTokenizer(new BufferedReader(reader));
		PrintWriter out = new PrintWriter(writer);
		int n = nextInt();
		long ans = 0;
		for (int vertex = 1; vertex <= n; vertex++) {
			int k = nextInt();
			make_set(vertex);
			for (int i = 0; i <  k; i++) {
				int v = nextInt();
				int x = nextInt();
				union_sets(v, vertex, x);
//				System.out.println(v + "|" + vertex + " = " + edge);
				ans = (ans + edge) % 1000000007L;
			}
		}
	   if (ans < 0)
            ans += 1000000007L;
		out.println(ans);
		out.flush();
		out.close();
	}
}