#include<stdio.h>
//#include<conio.h>
int n,p,i,s,c;

int main()

{

 freopen("fact.in","r",stdin);
 freopen("fact.out","w",stdout);

 scanf("%d",&p);

 if(p==0)

  printf("1");

 else
 
 for(i=5;s < p;i+=5)

 {

  c = i;

  while(c%5==0)

   {

    s++;

    c = c / 5;

   }

 }

 printf("%d",(i-5));
// getch();
return 0;

}