#include <iostream>
#include <string>
#include <sstream>

std::string nexttime(std::string nowtime) {
  std::string hs, ms, ss;
  std::istringstream nowstream(nowtime);
  std::getline(nowstream, hs, ':');
  std::getline(nowstream, ms, ':');
  std::getline(nowstream, ss);
  int h = std::stoi(hs);
  int m = std::stoi(ms);
  int s = std::stoi(ss);  
  /*-------------------------*/
  s++;
  if (s >= 60) { m++; s = 0; }
  if (m >= 60) { h++; m = 0; }
  if (h >= 24) h = 0;
  /*-------------------------*/
  hs = (hs = "0" + std::to_string(h)).substr(hs.size() - 2);
  ms = (ms = "0" + std::to_string(m)).substr(ms.size() - 2);
  ss = (ss = "0" + std::to_string(s)).substr(ss.size() - 2);
  return hs + ":" + ms + ":" + ss;
}

void f(std::string sin) {
  std::cout << sin << std::endl;
  std::cout << nexttime(sin) << std::endl << std::endl;
}

int main() {
  f("00:00:00");
  f("23:59:59");

  f("00:03:59");
  f("15:59:59");
  
  return 0;
}
/* end */