#include <fstream>

using namespace std;

ifstream in("fact.in");
ofstream out("fact.out");

int p, nr, n=0;
long long pas;

long long z(long long n){
    int nr=0;
    while(n!=0)
    {
        nr+=n/5;
        n=n/5;
    }
    return nr;
}

void fact(int p)
{
    pas = 1073741824;
    while(pas != 0)
    {
        if(z(n+pas) < p)
            n += pas;
        pas /= 2;
    }
    if(z(n+1) != p) out<<"-1";
    else out<<n+1;
}

int main()
{
    in>>p;
    fact(p);
    return 0;
}