#include <iostream>
#include <ctime>
int main(){
int time1 = 123456789;
std::time_t m = static_cast<time_t>(time1);
std::tm tm = *std::localtime(&m);
tm.tm_hour = 0;
tm.tm_min = 0;
tm.tm_sec = 0;
time_t timeSinceEpoch = mktime(&tm);
std::cout << timeSinceEpoch << std::endl;
}