#include <stdio.h>
#include <string.h>
#include <string>
#include <vector>
#include <sstream>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <map>
using namespace std;

#define FOR(i,n) for (int i = 0; i < n; i++)
#define abs(x) ((x)<0?(-(x)):(x))
#define REP(i,v) for (unsigned i = 0; i < v.size(); i++)
#define RL(i,v) for (unsigned i = 0; i < v.length(); i++)
typedef long long ll;

int main(void)
{
#ifdef __LOCAL__
	freopen("problem2.in", "r", stdin);
#else
	freopen("sunny.in", "r", stdin);
 	freopen("sunny.out", "w", stdout);
#endif
    char buf1[10];
    char buf2[10];
    int N;
    double result = 0;
    scanf("%d",&N);
    for(int n=0;n<N;n++) {
        int h1,m1,h2,m2;
        double u;
        scanf("%d:%d %s %d:%d %s %lf",&h1,&m1,&buf1,&h2,&m2,&buf2,&u);
        if(h1==12)h1 = 0;
        if(h2==12)h2 = 0;
        double hh1 = h1+m1/60.0;
        if(buf1[0]=='p')hh1+=12;
        double hh2 = h2+m2/60.0;
        if(buf2[0]=='p')hh2+=12;
        double temp = hh2-hh1;
        if(temp<0)temp+=24;
        result += (hh2-hh1)*u*sqrt(u);
    }
    printf("%.3f\n",result);
    return 0;
}
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