//
#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
int main()
{
    char z;
    string s,s1,s2,s3;
    int n,u,h,m,h1,m1;
    cin>>n;
    double ch=0,sum=0,u1;
    for(int i=0;i<n;i++)
    {
        cin>>s;
        cin.get(z);
        cin>>s1;
        cin.get(z);
        cin>>s2;
        cin.get(z);
        cin>>s3;
        cin>>u;
        //cout<<s<<" "<<s1<<" "<<s2<<" "<<s3<<" "<<u<<endl;
        h=int((s[0]-'0')*10+s[1]-'0');
        m=int((s[3]-'0')*10+s[4]-'0');
        if(s1=="pm" && h!=12){h=h+12;}
        if(s1=="am" && h==12){h=h+12;}
        
        h1=int((s2[0]-'0')*10+s2[1]-'0');
        m1=int((s2[3]-'0')*10+s2[4]-'0');
        if(s3=="pm" && h1!=12){h1=h1+12;}
        if(s3=="am" && h1==12){h1=h1+12;}
        
        m=h*60+m;
        m1=h1*60+m1;
        
        if(m>m1){m1=m1+60*24;}
        m=m1-m;
        
        u1=sqrt(u);
        ch=double(m/60.00);
        ch=double(ch*u*u1);
        sum=sum+ch;
    }
    cout<<fixed<<setprecision(3)<<sum<<endl;
    return 0;
}<!-- 0.0418s -->