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