#include <iostream>
#include <math.h>
#include <fstream>
#include <string>
#include <stdlib.h>
#include <iomanip>


using namespace std;

int main() 
{
	int N;
	string x;
	long double hour1=0;
	long double hour2=0;
	long double min1=0;
	long double min2=0;
	long double timee1=0;
	long double timee2=0;
	ifstream inFile;
	ofstream outFile;
	outFile.open("sunny.out");
	inFile.open("sunny.in");

	inFile >> x;

	N = atoi(x.c_str());
	long double sum = 0.0;
	for(int i=0; i<N; i++)
	{

		inFile >> x;
		
		hour1 = atoi(x.substr(0,2).c_str());
		min1 = atoi(x.substr(3,2).c_str());
		timee1 = min1/60;
		timee1 += hour1;
		inFile >> x;
		if(x.compare("pm") == 0)
		{
			hour1 += 12;
		}
		
		inFile >> x;
		
		hour2 = atoi(x.substr(0,2).c_str());
		min2 = atoi(x.substr(3,2).c_str());
		
		inFile >> x;
		if(x.compare("pm") == 0)
		{
			hour2 += 12;
		}

		timee2 = min2/60;
		timee2 += hour2;

		inFile >> x;
		long double U =  atoi(x.c_str());
		
		long double temp = ((timee2-timee1)*(U*sqrt(U)));


		sum+= temp;
	}
	outFile <<fixed<< setprecision(3)<<sum;
	inFile.close();
	outFile.close();
}<!-- 0.0498s -->