#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");

int main ()
{
    long i,s,j,p;
    fin>>p;
    if (p==0) fout<<1;
    else if (p<5) fout<<5*p;
    else for (i=p*4;i<=p*5;i=i+5)
    {
        s=0;
            for (j=5; j<=i; j=j*5)
        s=s+i/j;
            if(s>p) {fout<<-1; break;}
            else if (s==p) {fout<<i/5*5; break;}
    }
    return 0;
}