#include<bits/stdc++.h>
using namespace std;
int n,a[2000005],m,sj[]={0,31,60,91,121,152,182,213,244,274,305,335,366};
string s;
deque<int>q;
int zhuan(string s){
	int K=1,O=0;
	for(int i=s.size()-1;i>=0;i--) O+=K*(s[i]-'0'),K*=10;
	return O;
}
int miao(){
	int Y=sj[zhuan(s.substr(5,2))]*24*3600,H=zhuan(s.substr(8,2))*24*3600,S=zhuan(s.substr(11,2))*3600,F=zhuan(s.substr(14,2))*60,M=zhuan(s.substr(17,2))+Y+H+S+F;
	return M;
}
int main(){
	cin>>n>>m;
	getchar();
	while(getline(cin,s)){
		int x=miao();
		q.push_back(x);
		while(!q.empty()&&q.front()<=x-n) q.pop_front();
		if(q.size()>=m){
			cout<<s.substr(0,19);
			return 0;
		}
	}
	cout<<-1<<"\n";
	return 0;
}