# include <stdio.h>
# define nmax 1001
int a[nmax],b[nmax],f[nmax];
int n,i,j;
void add()
{
  int t=0,x,i;
  for (i=1;i<=b[0];i++){
    x=a[i]+b[i]+t;
    f[i]=x%10; t=x/10;
  }
  f[0]=b[0];
  if (t>0) f[++f[0]]=t;

}
int main ()
{
  freopen("nunta.in", "r",stdin);
  freopen("nunta.out","w",stdout);
  scanf("%d",&n);
  a[1]=b[0]=b[1]=1;
  for (i=2;i<=n;++i){
    add();
    for (j=1;j<=f[0];++j){
      a[j]=b[j];b[j]=f[j];
    }
    a[0]=b[0];b[0]=f[0];
  }
  if (n==1) printf("1");
   else for (i=b[0];i>0;--i)
	     printf("%d",f[i]);
  return 0;
}