#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;
typedef long long Int;

double sum=0.0;
double today;

Int INT(char ch)
{
    return (Int)ch-(Int)'0';
}

int main()
{
    freopen("sunny.in","r",stdin);
    freopen("sunny.out","w",stdout);
    
    Int n;
    Int i;
    char ch;
    Int h1,m1;
    Int h2,m2;
    Int mins1,mins2;
    Int type1,type2;
    Int len;
    double hours;
    double t;
    
    cin>>n;
    
    for (i=1;i<=n;i++)
    {
        cin>>ch;
        h1=10*INT(ch);
        cin>>ch;
        h1=h1+INT(ch);
        
        cin>>ch;
        
        cin>>ch;
        m1=10*INT(ch);
        cin>>ch;
        m1=m1+INT(ch);
        
        cin>>ch;
        
        if (ch=='a')
        type1=1;
        else
        type1=2;
        
        cin>>ch;
        //////////////////////////
        cin>>ch;
        h2=10*INT(ch);
        cin>>ch;
        h2=h2+INT(ch);
        
        cin>>ch;
        
        cin>>ch;
        m2=10*INT(ch);
        cin>>ch;
        m2=m2+INT(ch);
        
        cin>>ch;
        
        if (ch=='a')
        type2=1;
        else
        type2=2;
        
        cin>>ch;
        ////////////////////////////
        
        if (h1==12)
        h1=0;
        if (h2==12)
        h2=0;
        
        if (type1==2)
        h1+=12;
        if (type2==2)
        h2+=12;
        /////////////////////////////
        mins1=h1*60+m1;
        mins2=h2*60+m2;
        /////////////////////////////
        len=mins2-mins1;
        /////////////////////////////
        hours=((double)len)/60.0;
        
        cin>>t;
        
        today=( t*sqrt(t) )*hours;
        sum=sum+today;
    }
    
    printf("%4.3f\n",sum);
    return 0;
}