#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t = -1, i, j, flag = 0, mx = 0, z = -1;
  string s;
  cin >> s;
  flag = (s[s.length() - 1]) - '0';
  for (i = 0; i < s.length() - 1; i++) {
    j = s[i] - '0';
    if ((j) % 2 == 0) {
      if (flag > j) {
        t = i;
        break;
      } else {
        mx = j;
        z = i;
      }
    }
  }
  if ((t == -1) && (z == -1))
    cout << -1;
  else if (t != -1) {
    s[s.length() - 1] = (j + '0');
    s[i] = flag + '0';
    cout << s;
  } else {
    char ch = s[s.length() - 1];
    s[s.length() - 1] = (mx + '0');
    s[z] = ch;
    cout << s;
  }
  return 0;
}
