cmmcp

#include <iostream>
#define LL long long int
using namespace std;

int cmm_cif_para(LL n)
{
    int cmmcp=-1;
    if(n==0)
        cmmcp=0;
    else
        while(n)
        {
            if(n%10%2==0&&n%10>cmmcp)
                cmmcp=n%10;
            n/=10;
        }
    if(cmmcp==-1)
        return 10;
    else
        return cmmcp;
}

int main()
{
    LL n;
    cin>>n;
    cout<<cmm_cif_para(n)<<'\n';
    return 0;
}