#include<cstdio>

 #include<cstring>

 #include<vector>

 #include<algorithm>

 #define maxn 5005

 using namespace std;

 vector<int>ve;

 int mmb[]={,,,,,

 ,,,,,,};

 struct node

 {

     int st,end;

 }no[maxn];

 char s[];

 int lisan[maxn*];

 int main()

 {

     int t,year,month,day,hour,min,m,n,mi;

     scanf("%d",&t);

     while(t--)

     {

         ve.clear();

         scanf("%d%d",&n,&m);

         for(int i=; i<n; i++)

         {

             scanf("%s",&s);

             scanf("%d-%d-%d",&year,&month,&day);

             scanf("%d:%d",&hour,&mi);

             if(year==&&month>)

             no[i].st=(year-)*+mmb[month-]+(day-)*+hour*+mi+;

             else no[i].st=(year-)*+mmb[month-]+(day-)*+hour*+mi;

             ve.push_back(no[i].st);

             scanf("%d-%d-%d",&year,&month,&day);

             scanf("%d:%d",&hour,&mi);

             if(year==&&month>)

             no[i].end=(year-)*+mmb[month-]+(day-)*+hour*+mi+m+;

             else no[i].end=(year-)*+mmb[month-]+(day-)*+hour*+mi+m;

             if(no[i].end==no[i].st)

             ve.push_back(no[i].end+);

             else ve.push_back(no[i].end);

         }

         sort(ve.begin(),ve.end());

         ve.erase(unique(ve.begin(),ve.end()),ve.end());

         memset(lisan,,sizeof lisan);

         for(int i=; i<n; i++)

         {

             int pos=lower_bound(ve.begin(), ve.end(),no[i].st)-ve.begin();

             lisan[pos]+=;

             pos=lower_bound(ve.begin(), ve.end(),no[i].end)-ve.begin();

             lisan[pos]+=-;

         }

         int mii=;

         for(int i=; i<ve.size(); i++)

             if(i>)

                 lisan[i]+=lisan[i-];

         for(int i=; i<ve.size(); i++)

             if(lisan[i]>mii)mii=lisan[i];

         printf("%d\n",mii);

     }

     return ;

 }