using System;
using System.Linq;
class Program {
    static void Main() {
        long ans = 0;
        int n = int.Parse(Console.ReadLine());
        long mod = (long)1e9 + 7;
        for (int i = 0; i < n; i++) {
            long[] cd = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
            long cm = (cd[0] + 1) / 2 % mod;
            long dm = cd[1] % mod;
            ans += cm * dm % mod;
            ans %= mod;
        }
        Console.WriteLine(ans);
    }
}