#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <class T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <class T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <class T>
inline void printsp(T first) {
  print(first);
  putchar(' ');
}
template <class T>
inline void println(T first) {
  print(first);
  putchar('\n');
}
template <class T, class U>
inline void print(T first, U second) {
  printsp(first);
  println(second);
}
template <class T, class U, class V>
inline void print(T first, U second, V z) {
  printsp(first);
  printsp(second);
  println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
int root[111111];
long long w[111111];
long long dep[111111];
long long ans = 0;
int find_root(int v) {
  if (v == root[v]) return v;
  int u = root[v];
  int r = find_root(u);
  dep[v] += dep[u];
  dep[v] %= 1000000007;
  root[v] = r;
  return r;
}
void add_edge(int i, int v, int first) {
  int u = find_root(v);
  dep[u] = w[u] = (dep[v] + first + 1000000007) % 1000000007;
  root[u] = i;
}
int main() {
  int n;
  int k, v, first;
  gn(n);
  for (int i = 1; i <= n; i++) {
    root[i] = i;
    gn(k);
    if (k == 0) continue;
    for (int j = 0; j < k; j++) {
      gn(v, first);
      add_edge(i, v, first);
    }
  }
  for (int i = 1; i <= n; i++) {
    ans += w[i];
    ans %= 1000000007;
  }
  cout << ans;
  return 0;
}
