#include <stdio.h>

#include <memory.h>

#include <math.h>

#include <string>

#include <vector>

#include <set>

#include <stack>

#include <queue>

#include <algorithm>

#include <map>

#define I scanf

#define OL puts

#define O printf

#define F(a,b,c) for(a=b;a<c;a++)

#define FF(a,b) for(a=0;a<b;a++)

#define FG(a,b) for(a=b-1;a>=0;a--)

#define LEN 1010

#define MAX (1<<30)+1

#define V vector<int>

using namespace std;

struct Customer{

    int comeTime;

    int serveTime;

    Customer(int c,int s):comeTime(c),serveTime(s){

    }

};

bool cmp(Customer a,Customer b){

    return a.comeTime<b.comeTime;

}

int processTime(int H,int M,int S){

    return H*+M*+S;

}

int windowEnd[];//每个窗口的结束时间 

int main(){

//    freopen("1017.txt","r",stdin);

    int N,M,i,j,hh,mm,ss,p;

    I("%d %d",&N,&M);

    int startTime=processTime(,,);

    int endTime=processTime(,,);

    vector<Customer> C;

    FF(i,M) windowEnd[i]=startTime;    //初始化每个窗口的开始时间

    while(N--){

        I("%d:%d:%d %d",&hh,&mm,&ss,&p);

        int thisTime=processTime(hh,mm,ss);

        if(thisTime>endTime) continue;

        p*=;

        p=min(p,);        //处理排队超时

        C.push_back(Customer(thisTime,p));

    }

    sort(C.begin(),C.end(),cmp);

    int wait=;

    //对于每一个顾客进行处理

    FF(i,C.size()){

        //选择一个最早结束的

        int minTime=MAX,mI;

        FF(j,M) {

            if(windowEnd[j]<minTime){

                minTime=windowEnd[j];

                mI=j;

            }

        }

        if(windowEnd[mI]>C[i].comeTime){    //顾客来早了，需要等待

            wait+=windowEnd[mI]-C[i].comeTime;

            windowEnd[mI]+=C[i].serveTime;

        }else{        //顾客不用等待

            windowEnd[mI]=C[i].comeTime+C[i].serveTime;

        }

    }

    O("%.1f\n",wait/60.0/C.size());

    return ;

}