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

int zero(int poz)
{
    int suma=0;
    while(poz)
    {
        suma+=poz/5;
        poz/=5;
    }

    return suma;
}

int main ()
{
    int p,i,j;
    in>>p;
    long long dev;
    dev=1<<31;
    i=0;
    while(dev)
    {
        if(zero(i+dev)<p)
            i+=dev;
        dev/=2;
    }
    if(zero(i+1)==p)
        out<<i+1<<'\n';
    else
        out<<"-1\n";
    return 0;
}