#include<fstream.h>
long p,n;
int main()
{ int i,j;
  ifstream f("fact.in");
  f>>p;
  int ok=0,n2=0,n5=0;
  i=1;
  while(ok)
    { i++;
      j=i;
      if(j%2==0)
	 while(j%2==0)
	   { j=j/2;
	     n2++;
	   }
      if(j%5==0)
	 while(j%5==0)
	   { j=j/5;
	     n5++;
	   }
      if(n2==p && n2<=n5) ok=1;
      else if(n5==p && n5<=n2) ok=1;
    }
  ofstream g("fact.out");
  g<<i;
  g.close();
  f.close();
  return 0;
}