#include<bits/stdc++.h>
using namespace std;

int vec[10];

int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");

    int P;
    f >> P;

    if( P == 0)
        g << 1;
    else
        if( P%2 == 0 )
            g << (P - P/10)*5;
        else g << -1;
    f.close(); g.close();

    return 0;
}