#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define all(v) v.begin(), v.end()
using namespace std;
using ll = long long;

int main()
{
  string x, y;
  cin >> x;
  y = x;
  sort(all(x), greater<char>());
  if (x[0] == '0') { cout << -1 << endl; return 0; }
  swap(y[y.size()-1], y[y.size()-2]);
  if (y[0] == '0') { cout << -1 << endl; return 0; }
  if (y == x) { cout << -1 << endl; return 0; }
  cout << y << endl;
}