#include <stdio.h>
#define N 1005
int v1[N],v2[N],v3[N];
void add(int A[], int B[],int C[])
{
      int i, t = 0;
      for (i=1; i<=A[0] || i<=B[0] || t; i++, t/=10)
              C[i] = (t += A[i] + B[i]) % 10;
      C[0] = i - 1;
}
int main()
{
	freopen("nunta.in","r",stdin);
	freopen("nunta.out","w",stdout);
	int n,poz=0,i;
	scanf("%d",&n);
	v1[1]=1;
	v2[1]=1;
	v2[0]=1;
	v1[0]=1;
	poz=2;
	while (poz<=n)
	{
		add(v1,v2,v3);
		v1[0]=v2[0];
		for (i=v1[0]; i>=1; i--)
			v1[i]=v2[i];
		v2[0]=v3[0];
		for (i=v2[0]; i>=1; i--)
			v2[i]=v3[i];
		poz++;
	}
	for (i=v2[0]; i>=1; i--)
		printf("%d",v2[i]);
	return 0;
}