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

namespace Sunny
{
    class Program
    {
        static void Main(string[] args)
        {
            string inFile = System.IO.File.ReadAllText("sunny.in");
            string[] rows = inFile.Split(new char[]{'\n', '\r'}, StringSplitOptions.RemoveEmptyEntries);
            int daysCount = int.Parse(rows[0]);
            double energy = 0;
            for (int i = 1; i <= daysCount; i++)
            {
                string[] dayInfo = rows[i].Split(' ');
                int dayStart = HourInMins(dayInfo[0], dayInfo[1]);
                int dayEnd = HourInMins(dayInfo[2], dayInfo[3]);
                int dayInMin = dayEnd - dayStart;
                if (dayInMin < 0)
                {
                    dayInMin += 24 * 60;
                }
                int temp = int.Parse(dayInfo[4]);
                energy += (dayInMin * temp * Math.Sqrt(temp)) / 60;
            }
            System.IO.File.WriteAllText("sunny.out", String.Format("{0:0.###}", energy));
        }

        public static int HourInMins(string hour, string amPm)
        {
            int minsTotal = 0;
            int hr = int.Parse(hour.Split(':')[0]);
            int min = int.Parse(hour.Split(':')[1]);
            if (amPm == "am")
            {
                hr = hr % 12;
            }
            else
            {
                hr = (hr % 12) + 12;
            }
            minsTotal = hr * 60 + min;
            return minsTotal;
        }
    }
}