#include <bits/stdc++.h>
using namespace std;
int day[13] = {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366};
int sec, n, k, dd, mm, h, s, m, now;
string str;
queue<int> q;
int main() {
  cin >> sec >> k;
  getline(cin, str);
  while (scanf("2012-%d-%d %d:%d:%d:", &mm, &dd, &h, &m, &s) != EOF) {
    getline(cin, str);
    now = (day[mm - 1] + dd - 1) * 24 * 60 * 60 + h * 60 * 60 + m * 60 + s;
    q.push(now);
    while (q.front() + sec <= now) q.pop();
    if (q.size() >= k) {
      printf("2012-%02d-%02d %02d:%02d:%02d", mm, dd, h, m, s);
      return 0;
    }
  }
  cout << -1 << endl;
  fclose(stdout);
  return 0;
}
