#include<fstream.h>
int a[310],b[310],c[310];
int main()
{
	ifstream f("nunta.in");
	ofstream g("nunta.out");
	int n,k=0,i,t=0,j;
	b[1]=1;
	f>>n;
	if (n<4)
	{
		if (n==1) {g<<1;return 0;}
		if (n==2) {g<<2;return 0;}
		if (n==3) {g<<3;return 0;}		
	}
	else
	{
	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=1000;i>=1;i--)
		if (c[i]!=0) break;
	for (j=i;j>=1;j--)
		g<<c[j];
	}
	return 0;
}