#include <cassert>
#include <cmath>
#include <concepts>
#include <iomanip>
#include <iostream>
#include <string>
#include <string_view>

template <std::integral T>
T binexp(T base, T exponent, T mod) {
  assert(mod > 0 && exponent > 0);

  T product{1};
  T multiplier{base % mod};

  while (exponent > 0) {
    if ((exponent & 1) != 0) {
      product = (multiplier * product) % mod;
    }
    multiplier = (multiplier * multiplier) % mod;
    exponent >>= 1;
  }

  return product;
}

int main() {
  using namespace std::string_view_literals;

  std::string S{"hello"};
  std::string_view s{S};
  S.~basic_string();

  // double ub - free + string view dereferencing destroyed object
  // std::cout << s << '\n' ;

  std::cout << -5 / 2 << '\n';

  using namespace std;
  long double ld = pow((long double)10, 18);  // computed in floating point
  long long ll = (long long)ld;               // cast back to integer

  cout << fixed << setprecision(0);
  cout << "pow(10,18) as long double: " << ld << "\n";
  cout << "cast to long long:         " << ll << "\n";
  cout << "Should be exactly:         " << 1000000000000000000LL << "\n";

  std::cout << binexp(2, 5, 5);

  return 0;
}