TruckTour

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

namespace _07._TruckTour
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            string[] pumpStations = new string[n];

            for (int i = 0; i < n; i++)
            {
                pumpStations[i] = Console.ReadLine();
            }
            Queue<string> pumps = new Queue<string>(pumpStations);


            for (int i = 0; i < n; i++)
            {
                bool isValid = true;
                int tank = 0;
                for (int j = 0; j < n; j++)
                {
                    string station = pumps.Dequeue();
                    int[] paramaters = station.Split().Select(int.Parse).ToArray();
                    int fuel = paramaters[0];
                    int distance = paramaters[1];
                    tank += fuel;
                    tank -= distance;
                    if (tank < 0)
                    {
                        isValid = false;
                    }
                    pumps.Enqueue(station);

                }
                if (isValid)
                {
                    Console.WriteLine(i);
                    return;
                }
                pumps.Enqueue(pumps.Dequeue());
            }
        }
    }
}