#include <bits/stdc++.h>
const long long int mod = 1e9 + 7;
const long double Pi = acos(-1);
const long double euler = log(15.1542622);
using namespace std;
bool isPrime(long long int n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (int i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
bool isPerfect(long long int n) {
  long long int x = sqrt(n);
  if (x * x == n)
    return true;
  else
    return false;
}
void sai() {
  string s;
  int temp, count = 0, count1 = 0;
  cin >> s;
  int n = s.length();
  for (int i = 0; i < n - 1; i++) {
    if (!(int(s[i] % 2))) {
      count++;
      if (int(s[n - 1]) > int(s[i])) {
        swap(s[i], s[n - 1]);
        cout << s;
        count1++;
        break;
      } else
        temp = i;
    }
  }
  if (count == 0)
    cout << -1;
  else if (count1 == 0) {
    swap(s[temp], s[n - 1]);
    cout << s;
  }
}
int main() {
  int t = 1;
  while (t--) {
    sai();
  }
  return 0;
}
