#include<stdio.h>
#include<string.h>
#define N 1000
int n,x[N]={1,1},y[N]={1,1},z[N]={1,2},aux[N];
/*int fib(int n)
{
	int i,x,y,z;
	x=y=1;
	z=x+y;
	for(i=3;i<=n;i++)
	{
		x=y;
		y=z;
		z=x+y;
	}
	return z;
}*/
void suma(int v1[N],int v2[N],int rez[N])
{
	int i,t=0,k=1,sum[N];
	memset(sum,0,sizeof(sum));
	for(i=1;i<=v1[0]&&i<=v2[0];i++)
	{
		sum[k++]=(v1[i]+v2[i]+t)%10;
		t=(v1[i]+v2[i]+t)/10;
	}
	while(i<=v1[0])
	{
		sum[k++]=(v1[i]+t)%10;
		t=(v1[i]+t)/10;
		i++;
	}
	while(i<=v2[0])
	{
		sum[k++]=(v2[i]+t)%10;
		t=(v2[i]+t)/10;
		i++;
	}
	if(t)
		sum[k++]=t;
	sum[0]=k-1;
	memcpy(rez,sum,sizeof(sum));
}
void fibo()
{
	int i;
	for(i=3;i<=n;i++)
	{
		memcpy(x,y,sizeof(y));
		memcpy(y,z,sizeof(z));
		suma(x,y,z);
	}
}
void afis()
{
	int i;
	for(i=z[0];i>=1;i--)
		printf("%d",z[i]);
	printf("\n");
}
int main()
{
	freopen("nunta.in","r",stdin);
	freopen("nunta.out","w",stdout);
	scanf("%d",&n);
	if(n==1)
	{
		printf("1\n");
		return 0;
	}
	if(n==2)
	{
		printf("2\n");
		return 0;
	}
	//printf("%d\n",fib(n));
	fibo();
	afis();
	return 0;
}