#include<stdio.h>
long p,n,x,f5;
int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    scanf("%ld",&p);
    if(p!=0)
    {
       n=4;
       do
       {
              n++;
              x=n;
              while(x%5==0)
              {             
                     f5++;
                     x/=5;
              }
       }
       while(f5<p);
       printf("%ld",n);
    }
    else printf("1");
    return 0;
}