#include <bits/stdc++.h>

using namespace std;

#define rep(i, n) for (int i = 0; i < (int)n; ++i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define each(i,c) for(__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define all(v) v.begin(), v.end()
#define mset(a, n) memset(a, n, sizeof(a))

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

const int inf = 1000000000;
const int mod = 1000000007;
const double eps = 1e-9;

int main() {
	// cin.tie(0); // tie
	// ios::sync_with_stdio(false); // sync
	string N; cin >> N;
	sort(all(N));
	reverse(all(N));
	cout << N << endl;
	return 0;
}