/*
User ID: Tanmoy_Datta
Link : http://codeforces.com/problemset/problem/508/B
*/

#include <bits/stdc++.h>

#define pii pair <int,int>
#define sc scanf
#define pf printf
#define Pi 2*acos(0.0)
#define ms(a,b) memset(a, b, sizeof(a))
#define pb(a) push_back(a)
#define MP make_pair
#define oo 1<<29
#define dd double
#define ll long long
#define EPS 10E-10
#define ff first
#define ss second
#define MAX 120
#define SZ(a) (int)a.size()
#define getint(a) scanf("%d",&a)
#define loop(i,n) for(int i=0;i<n;i++)
#define all(a) a.begin(),a.end()
#define intlim 2147483648
#define inf 100000
#define rtintlim 46340
#define llim 9223372036854775808
#define rtllim 3037000499
#define ull unsigned long long
#define I int

using namespace std;

int main()
{
    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);
    string str;
    cin>>str;
    int lenth=SZ(str);
    int last=str[lenth-1]-'0';
    int a=0;
    int pos=-1,val=-1,dif=1000;
    for(int i=0; i<lenth-1; i++)
    {
        int d=(str[i]-'0');
        if(d%2==0)
        {
            if(last>d)
            {
                char c=str[i];
                str[i]=str[lenth-1];
                str[lenth-1]=c;
                a=1;
                break;
            }
            else
                pos=i;
        }
    }
    if(a)
        cout<<str<<endl;
    else
    {
        if(pos!=-1)
        {
            char c=str[pos];
            str[pos]=str[lenth-1];
            str[lenth-1]=c;
            cout<<str<<endl;
        }
        else
            cout<<-1<<endl;
    }
    return 0;
}