#include <iostream>
#include <ctime>
#include <cassert>
#include <fmt/core.h>
int main(int argc, char* argv[]) {
std::string format{argv[1]};
char buffer[1024] = {0};
time_t t;
struct tm *tmp = nullptr;
t = time(NULL);
tmp = localtime(&t);
assert(tmp != NULL && "Invalid time.");
strftime(buffer, sizeof(buffer), format.c_str(), tmp);
fmt::println("{}", buffer);
}