#include<fstream.h>
ifstream f("fact.in");
ofstream g("fact.out");
int S;
int main()
{ int m,n;long p;f>>p;if(!p) { g<<"1";return 0; }
  n=5; while(S<p) { m=n;
                        while(m%5==0) { S++;
                                        m/=5;
                                      } 
                    n+=5;
                  }             g<<n-5;return 0;
}