#include <iostream>
#include <iomanip>
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed << std::setprecision(2);
  std::string s;
  std::cin >> s;
  ll dig[10];
  std::fill(dig, dig+10, 0);
  for (auto c : s) dig[c-'0']++;
  for (int i = 9; i >= 0; --i) {
    for (int j = 0; j < dig[i]; ++j) std::cout << i;
  }
  std::cout << std::endl;
  return 0;
}