#include <fstream>
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <queue>
#include <map>
#include <set>
#include <cmath>
#include <iomanip>
#define pb push_back
#define mp make_pair
#define sortvi(a) sort(a.begin(), a.end())
#define FOR(i, start, final) for (int i=start; i<=final; ++i)
#define ROF(i, start, final) for (int i=start; i>=final; --i)

#define f cin
#define g cout

//void f(int &x){char k;for(k=getchar();k<= 32;k=getchar());for(x=0;'0'<=k;k=getchar())x=x*10+k-'0';}


/*void f(int &x)//parsare cu semn
{
	char k; bool semn=0;
	for (k = getchar(); (k>'9' || k<'0');)
    {
        if (k=='-') semn=1;
        k=getchar();
    }
	for (x = 0; '0' <= k; k = getchar())	x = x * 10 + k - '0';
    if (semn==1) x=-x;
}*/


using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair < int, int> pi;
typedef vector< int > vi;
typedef vector< pair< int, int > > vpi;

int N, poz;
char s[100005];

int main()
{
    f.sync_with_stdio(false);
    f>>(s+1); N=strlen(s+1);
    FOR(i,1,N)
        if ( (s[i]-'0')%2==0 )
        {
            if (s[i]<s[N])
            {
                swap(s[i], s[N]);
                FOR(i,1,N)g<<s[i]; g<<'\n';
                return 0;
            }
            poz=i;
        }

    if (poz==0){g<<-1<<'\n'; return 0;}
    swap(s[poz], s[N]);
    FOR(i,1,N)g<<s[i]; g<<'\n';
    return 0;
}