#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g ("fact.out");
int p;
int nrzero(int x)
{
    int exp;
    exp=0;
    while(x>1)
    {
        exp+=x/5;
        x=x/5;
    }
    return exp;
}
int gasirenr()
{
    int s=1,n,m,k,aux=0;
    long long d=1500000000;
    while(s<=d)
    {
        m=(s+d)/2;
        k=nrzero(m);
    if(k>=p)n=m,d=m-1,aux=k;
        else s=m+1;
    }
    if(nrzero(n)!=aux)g<<-1;
    else g<<n;
    return 0;
}
int main()
{
    f>>p;
    if(p==0)g<<1;
    else
        gasirenr();
    return 0;
}