using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static long[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var map = NArr(n);

        var tall = 0L;
        for (var i = 0; i < n; ++i) tall = (tall + map[i][0]) % mod;
        var left = 0L;
        var sum = 0L;
        var ans = 0L;
        for (var i = 0; i < n; ++i)
        {
            sum = (sum + map[i][0]) % mod;
            var cur = (Calc(tall, sum) - left + mod) % mod;
            left = (left + cur) % mod;
            ans = (ans + cur * map[i][1] % mod) % mod;
        }
        WriteLine(ans);
    }
    static int mod = 998_244_353;
    static int rev24 = 291_154_603;
    static long Calc(long t, long x)
    {
        return rev24 * x % mod * (x + 1) % mod * (x + 2) % mod * ((4 * t - 3 * x + 3 + mod) % mod) % mod;
    }
}