#include<cstdio>
using namespace std;
int a[301],b[301],c[301];
int main()
{
	freopen("nunta.in","r",stdin);
freopen("nunta.out","w",stdout);
	int n,k=0,i,t=0,j;
	b[1]=1;
	scanf("%d",&n);
	if (n<4)
	{
		printf("%d",n);
return 0;		
	}
	while (k<n)
	{
		
		for (i=1;i<=n;i++)
		{			
			c[i]=a[i]+b[i]+t;
			t=c[i]/10;
			c[i]%=10;
		}
		for (i=1;i<=n;i++)
		{
			a[i]=b[i];
			b[i]=c[i];
		}
		k++;
	}
	for (i=300;i>=1;i--)
		if (c[i]!=0) 
break;
	for (j=i;j>=1;j--)
		printf("%d",c[j]);
	return 0;
}