using System;
using System.Collections.Generic;
using System.IO.Pipes;
using System.Linq;

class Program
{
  
  public static int Main()
  {
    Scanner cin = new Scanner();
    int n = cin.nextInt();
    long ans = 0;
    for (int i = 0; i < n; i++)
    {
      ans += (((cin.nextLong() + 1) / 2) % 1000000007) * (cin.nextLong() % 1000000007);
      ans %= 1000000007;
    }
    Console.WriteLine(ans);
    return 0;
  }
}

class Scanner {
  string[] s;
  int i;

  char[] cs = new char[] { ' ' };

  public Scanner() {
    s = new string[0];
    i = 0;
  }

  public string next() {
    if (i < s.Length) return s[i++];
    do {
      s = Console.ReadLine().Split(cs, StringSplitOptions.RemoveEmptyEntries);
    } while ((s.Length == 1 && s[0] == "") || s.Length == 0);
    i = 0;
    return s[i++];
  }

  public int nextInt() {
    return int.Parse(next());
  }

  public long nextLong() {
    return long.Parse(next());
  }

  public double nextDouble() {
    return double.Parse(next());
  }

}