#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

int main()
{
	std::string X;
	in >> X;

	std::sort(X.rbegin(), X.rend());
	auto s1 = X;
	std::swap(X[X.length() - 2], X[X.length() - 1]);
	auto s2 = X;

	out << ((s1 == s2 || s2[0] == '0') ? "-1" : s2) << std::endl;
}