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.util.*;
import java.io.*;

public class Main {

	BufferedReader in;
	StringTokenizer str = null;
	PrintWriter out;
	
	private String next() throws Exception{
		while (str == null || !str.hasMoreElements())
			str = new StringTokenizer(in.readLine());
		return str.nextToken();
	}
	
	private int nextInt() throws Exception{
		return Integer.parseInt(next());
	}
	
	private long nextLong() throws Exception{
		return Long.parseLong(next());
	}
	
	private double nextDouble() throws Exception{
		return Double.parseDouble(next());
	}

	int []p, weight;
	// Bit bit;

	int []parent;

	final static int MODULE = (int)(1e9) + 7;
	
	public void run() throws Exception{
		in =  new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out);

		int q = nextInt(), n = q;

		// bit = new Bit(q + 10);

		p = new int[n + 1];
		for(int i = 1; i <= n; ++i) p[i] = i;
		weight = new int[n + 1];

		parent = new int[n + 1];
		Arrays.fill(parent, -1);

		int curV = 0;
		while(q-- > 0) {
			++curV;
			int k = nextInt();
			for(int i = 0; i < k; ++i) {
				int v = nextInt();
				int x = nextInt();

				// System.out.println(curV + " " + v + " " + x);

				int root = find(v);
				// System.out.println("root(" + v + ") = " + root);
				// System.out.println("weight(" + v + ") = " + weight[v]);
				int w = weight[v] + x;
				if (w >= MODULE) w -= MODULE;
				if (w < 0) w += MODULE;
				// System.out.println("weight for " + root + " is " + w);
				weight[root] = w;
				// bit.update(root, w);
				union(root, curV);
				parent[root] = curV;
				// System.out.println("p");
				// for(int j = 1; j <= n; ++j) {
				// 	System.out.println(j + " -> " + p[j] + ", ");
				// }
				// System.out.println();
				// System.out.println("w");
				// for(int j = 1; j <= n; ++j) {
				// 	System.out.println(j + " -> " + weight[j] + ", ");
				// }
			}
		}
		// int sum = 0;
		// for(int i = 1; i <= n; ++i) sum += weight[i];
		// out.println(sum);
		// System.out.println("parents");
		// for(int i = 1; i <= n; ++i)
		// 	System.out.println(i + " " + parent[i]);
		
		for(int i = 1; i <= n; ++i) find(i);

		// System.out.println("weights");
		// for(int i = 1; i <= n; ++i)
		// 	System.out.println(i + " " + weight[i]);
		// System.out.println("p");
		// for(int i = 1; i <= n; ++i)
		// 	System.out.println(i + " " + p[i]);
		int sum = 0;
		for(int i = 1; i <= n; ++i)
			if (parent[i] != -1) {
				sum += weight[i] - weight[parent[i]];
				if (sum >= MODULE) sum -= MODULE;
				if (sum < 0) sum += MODULE;
			}

		out.println(sum);
		out.close();
	}

	private int find(int x) {
		if (x != p[x]) {
			int prev = p[x];
			p[x] = find(p[x]);
			weight[x] += weight[prev];
			if (weight[x] >= MODULE)
				weight[x] -= MODULE;
			return p[x];
		}
		return x;
	}

	private void union(int a, int b) {
		a = find(a);
		b = find(b);

		p[a] = b;
	}

	// class Bit {
	// 	int []tree;
	// 	public Bit(int n) {
	// 		tree = new int[n];
	// 	}

	// 	public int sum(int l, int r) {
	// 		int sum = sum(r) - sum(l - 1);
	// 		return sum;
	// 	}

	// 	public int sum(int x) {
	// 		int sum = 0;
	// 		while(x > 0) {
	// 			sum += tree[x];
	// 			x -= x & -x;
	// 		}
	// 		return sum;
	// 	}

	// 	private void update(int x, int delta) {
	// 		while(x < tree.length) {
	// 			tree[x] += delta;
	// 			x += x & -x;
	// 		}
	// 	}
	// }

	public static void main(String[] args) throws Exception{
		new Main().run();
	}
}