#include<iostream>
#include<fstream>
long long suma_5(long long i)
{long long aux=i,sum=0;
while(aux!=0)
{sum+=aux%5;aux/=5;}   
return sum;
     }
  using namespace std;             
                 ifstream f("factorial.in");
                 ofstream g("factorial.out");

int main()
{
    long long i,p;
    f>>p;
    f.close();
               for(i=1;0==0;i++)
               if (i-suma_5(i)==4*p) {g<<i;break;}
               else if (i-suma_5(i)>4*p) {g<<"-1";break;}                               
    g.close();
     }