#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
using namespace std;

int main()
{
	int hour=0, min=0;
	double getHour1=0, getMin1=0, getHour2=0, getMin2=0;
	int t=0;
//	int ch1, ch2;
	string noon1, noon2;
	long double energy=0.0;
	char h1[6], h2[6];
	char conv1[3], conv2[3];

	ifstream in;
	in.open("sunny.in");
	FILE* out;
	out=fopen("sunny.out", "w");
	
	int count=0;
	in>>count;

	while(count-- > 0)
	{
		in>>h1>>noon1>>h2>>noon2>>t;
		conv1[0]=h1[0];
			conv1[1]=h1[1];
			conv1[2]='\0';
			conv2[0]=h2[0];
			conv2[1]=h2[1];
			conv2[2]='\0';
			getHour1=atoi(conv1);
			getHour2=atoi(conv2);
			conv1[0]=h1[3];
			conv1[1]=h1[4];
			conv1[2]='\0';
			conv2[0]=h2[3];
			conv2[1]=h2[4];
			conv2[2]='\0';
			getMin1=atoi(conv1);
			getMin2=atoi(conv2);
		if(noon1 == noon2)
		{
			if(getMin2 < getMin1)
			{
				min=static_cast<int>(getMin2-getMin1+60);
				if((hour=static_cast<int>(getHour2-getHour1)) <= 1)
				{
					hour=0;
				}
				else
				{
					hour=static_cast<int>(getHour2-getHour1);
				}
			}
			else
			{
				min=static_cast<int>(getMin2-getMin1);
				if((hour=static_cast<int>(getHour2-getHour1)) <= 0)
				{
					hour=0;
				}
				else
				{
					hour=static_cast<int>(getHour2-getHour1);
				}
			}
		//	energy+=hour*t*sqrt((double)t)+((double)min/60)*t*sqrt((double)t);
			double time=(double)hour;
			double mins=((double)min/60);
			energy+=(time+mins)*pow(double(t), 1.5);
		}
		else
		{
			if(getMin2 < getMin1)
			{
				min=static_cast<int>(getMin2-getMin1+60);
				if((hour=static_cast<int>(getHour2-getHour1)) == 1)
				{
					hour=0;
				}
				else
				{
					hour=static_cast<int>(getHour2-getHour1+11);
				}
			}
			else
			{
				min=static_cast<int>(getMin2-getMin1);
				if((hour=static_cast<int>(getHour2-getHour1)) == 0)
				{
					hour=0;
				}
				else
				{
					hour=static_cast<int>(getHour2-getHour1+12);
				}
			}
		//	energy+=hour*t*sqrt((double)t)+((double)min/60)*t*sqrt((double)t);
			double time=(double)hour;
			double mins=((double)min/60);
			energy+=(time+mins)*pow(double(t), 1.5);
		}
	}

	printf("%.3f\n", energy);
	fprintf(out, "%.3f\n", energy);
	in.close();
	fclose(out);
	return 0;
}<!-- 0.0394s -->