#define _CRT_SECURE_NO_DEPRECATE
#include <iostream> 
#include <string>
#include <vector>
#include <sstream>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <math.h>
#include <stack>
#include <deque>
#include <numeric>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <bitset>
#define mpair make_pair
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
typedef long double ld;
const ld epsylon = 1e-9;

struct mtime{
  int minutes;

};


istream& operator>>(istream& in, mtime& t) {
  string t1,t2;
  in >> t1 >> t2;

  t1[2] = ' ';
  istringstream iss(t1);

  int h, m;
  iss >> h >> m;
  t.minutes = h*60 + m;

  if (t2 == "pm") {
    if (h == 12){ 
      t.minutes += 0;
    } else {
      t.minutes += 12*60;
    }
  }

  //if (t2 == "am" && h == 12 && m == 0) {
  //  t.minutes += 12 * 60;
  //}
  return in;
}
int main()
{
  freopen("sunny.in","r",stdin);
  freopen("sunny.out", "w", stdout);

  int n;
  cin >> n;

  ld res= 0;
  for (int i =0;i<n;++i){
    mtime a,b;
    ld v;
    cin >> a >> b >> v;

    ll temp = (ll)b.minutes - (ll)a.minutes;

    if (temp < 0) {
      temp += 24 * 60;
    }
    res += ((ld)temp/((ld)60.0)) * pow(v, (ld)1.5);
  }

  printf("%.3lf\n", (double)res);
  return 0;
}
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