#include <cstdio>

int nrfact(int x)
{
    int n2=0,n5=0;
    for(int i=1;i<=x;i++)
        {if(i%2==0)
        {
            int aux=i;
         while(aux%2==0)
          n2++,aux/=2;
        }
         if(i%5==0)
        {
            int aux=i;
         while(aux%5==0)
          n5++,aux/=5;
        }
        }
    if(n2<n5)
        return n2;
    return n5;
}

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
  int x;
  scanf("%d",&x);
  int fact;
  int ok=0;
  for(int i=1;ok!=1;i++)
    if(nrfact(i)==x)
  {
      ok=1;
      fact=i;
  }
  printf("%d",fact);
    return 0;
}