#include <bits/stdc++.h>
using namespace std;
vector<int>a(1500,0);
int convertTimeToMin(string time){
int hh,mm;
sscanf(time.c_str(),"%d:%d",&hh,&mm);
return hh*60 + mm;
}
string minToHour(int startTime) {
int hh = startTime / 60;
int mm = startTime % 60;
stringstream ss;
ss << setw(2) << setfill('0') << hh << ":" << setw(2) << setfill('0') << mm;
return ss.str();
}
string solve(vector<string>& input , int k){
fill(a.begin(),a.end(),0);
string ans;
for(const auto& st:input){
stringstream ss(st);
string name,action,time1,time2;
ss>>name>>action>>time1>>time2;
int v1 = convertTimeToMin(time1);
int v2 = convertTimeToMin(time2);
a[v1] += 1;
a[v2+1] += -1;
}
for(int i=1;i<a.size();i++){
a[i] = a[i-1] + a[i];
}
int freeTime=0;
for(int i=0;i<a.size();i++){
if(a[i]==0){
freeTime++;
if(freeTime==k){
int startTime = i-k+1;
ans = minToHour(startTime);
break;
}
}
else{
freeTime=0;
}
}
return ans;
}
int main() {
int n;
cin>>n;
int k;
cin>>k;
cin.ignore();
vector<string>input(n);
for(int i=0;i<n;i++){
getline(cin,input[i]);
}
string ans = solve(input,k);
cout<<ans<<endl;
return 0;
}
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