#include <fstream>

using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int n, fact, aux, sw,k;
int main()
{
    fin>>n;
    if(n==0) k=1;


    while(n>0)
    {
        sw=0;
        fact=fact+5;
        aux=fact;
        while(aux%5==0)
            {aux=aux/5; sw++;}
        n=n-sw;

    }

        if(n==0&&k==0)fout<<fact;
        else if(k==1) fout<<"1";
        else fout<<"-1";

    return 0;
}