#include <fstream>

using namespace std;

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

int zero(int n)
{
    int nr=0;
    while(n>=5)
    {
        nr+=n/5;
        n/=5;
    }
    return nr;
}
int main()
{
    int r;
    long long pas,p;
    pas=1<<28;
    in>>p;
    r=0;
    while(pas!=0)
    {
        if(zero(r+pas)<p)
        {
            r+=pas;
        }
        pas/=2;
    }
    r++;
    if(zero(r)!=p)
    {
        r=-1;
    }
    out<<r;
    return 0;
}