#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int a[10];
int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  string s;
  cin>>s;
  rep(i,s.size())a[s[i]-'0']++;
  for(int i=9;i>=0;i--)while(a[i]){cout<<i;a[i]--;}
  cout<<endl;
}