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.Closeable;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.Collection;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Jacob Jiang
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		QuickScanner in = new QuickScanner(inputStream);
		ExtendedPrintWriter out = new ExtendedPrintWriter(outputStream);
		TaskE solver = new TaskE();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskE {
    int[] parent;
    private int n;
    private long[] depth;
    final long mod = 1000000007;

    public void solve(int testNumber, QuickScanner in, ExtendedPrintWriter out) {
        n = in.nextInt();
        depth = new long[n];
        parent = new int[n];
        for (int i = 0; i < n; i++) {
            parent[i] = i;
        }
        long answer = 0;
        for (int cur = 0; cur < n; cur++) {
            int k = in.nextInt();
            int[] v = new int[k];
            long[] x = new long[k];
            for (int i = 0; i < k; i++) {
                v[i] = in.nextInt();
                x[i] = in.nextLong();
            }
            ArrayUtils.decreaseByOne(v);
            for (int i = 0; i < k; i++) {
                int son = find(v[i]);
                depth[son] = (depth[v[i]] + x[i]) % mod;
                answer = (answer + depth[son]) % mod;
                parent[son] = cur;
                find(v[i]);
            }
        }
        if (answer < 0) {
            answer += mod;
        }
        out.print(answer);
	}

    int find(int current) {
        int oldParent = parent[current];
        if (oldParent == current) {
            return current;
        }
        int newParent = find(oldParent);
        if (oldParent != newParent) {
            parent[current] = newParent;
            depth[current] = (depth[current] + depth[oldParent]) % mod;
        }
        return newParent;
    }
}

class QuickScanner implements Iterator<String>, Closeable {
    BufferedReader reader;
    StringTokenizer tokenizer;
    boolean endOfFile = false;

    public QuickScanner(InputStream inputStream){
        reader = new BufferedReader(new InputStreamReader(inputStream));
        try {
            tokenizer = new StringTokenizer(reader.readLine());
        } catch (Exception e) {
            endOfFile = true;
        }
    }

    public boolean hasNext() {
        if (!tokenizer.hasMoreTokens()) {
            try {
                checkNext();
            } catch (NoSuchElementException ignored) {
            }

        }
        return !endOfFile;
    }

    private void checkNext() {
        if (endOfFile) {
            throw new NoSuchElementException();
        }
        try {
            while (!tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
        } catch (Exception e) {
            endOfFile = true;
            throw new NoSuchElementException();
        }
    }

    public String next() {
        checkNext();
        return tokenizer.nextToken();
    }

    public void remove() {
        throw new UnsupportedOperationException();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public void close() {
        try {
            reader.close();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }


}

class ExtendedPrintWriter extends PrintWriter {


    public ExtendedPrintWriter(Writer out) {
        super(out);
    }

    public ExtendedPrintWriter(OutputStream out) {
        super(out);
    }

    }

class ArrayUtils {

    public static void decreaseByOne(int[]... arrays) {
        for (int[] array : arrays) {
            for (int i = 0; i < array.length; i++) {
                array[i]--;
            }
        }
    }

    }