using System;
using System.Linq;

namespace _146
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            long ret = 0; int mod = (int)Math.Pow(10,9) + 7;
            for (int i = 0; i < n; i++)
            {
                long[] x = Console.ReadLine().Split().Select(long.Parse).ToArray();
                x[0] = (x[0] + 1) / 2;
                long a = x[0]; a %= mod;
                a *= x[1]; a %= mod;
                ret += a; ret %= mod;
            }
            Console.WriteLine(ret);
        }
    }
}