#include <iostream>
#include <fstream>
using namespace std;
int v[100000000];
ifstream f("fact.in");
ofstream g("fact.out");

int main()
{int p, n=0 ,i,aux,save;
f>>p;if(p==0)cout<<"1";
while(aux!=p)
{

  n++;
    save=n;
for(i=2;i<=n;i++)
    if(save%i==0)
    {save=save/i;
    v[i]++;
    i--;}
if(v[2]<=v[5])
   aux=v[2];
if(v[2]>v[5])
    aux=v[5];

} g<<n;
}