#include <cstdio>
unsigned char A[210],B[210];int n,i,j,r,aux;main(){freopen("nunta.in","r",stdin);freopen("nunta.out","w",stdout);scanf("%d",&n);A[0]=A[1]=B[0]=B[1]=1;for(i=2;i<=n;++i){r=0;for(j=1;j<=B[0]||r;++j){r+=(A[j]+B[j]);aux=B[j];B[j]=r%10;A[j]=aux;r/=10;}A[0]=B[0];B[0]=j-1;}for(i=B[0];i;--i)fputc(B[i]+'0',stdout);}