using System;
using System.Collections.Generic;
using System.Linq;

namespace No236
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var n = Convert.ToInt32(Console.ReadLine ());
			long sum = 0;
			long mod = 1000000007L;
			for (int i = 0; i < n; i++) {
				var line = Console.ReadLine ().Split (' ').Select (v => Convert.ToInt64 (v)).ToArray ();
				var c = ((line [0] + 1L) / 2L) % mod;
				var d = line [1] % mod;
				var cd = (c * d) % mod;
				sum += cd;
				sum %= mod;
			}
			Console.WriteLine (sum.ToString ());
		}
	}
}