#include <cstdio>
struct Huge{unsigned char v[213];Huge(){for(int i=0;i<213;++i)v[i]=0;}Huge operator+(Huge &other){Huge aux;int i, t=0;for(i=1;i<=v[0]||i<=other.v[0]||t;++i,t/=10)aux.v[i]=(t+=v[i]+other.v[i])%10;aux.v[0]=i-1;return aux;}}a,b,c;int main(){int n;fscanf(fopen("nunta.in","r"),"%d",&n);a.v[0]=a.v[1]=1;b=c=a;for(int i=1;i<n;++i){c=a+b;a=b;b=c;}FILE*fout=fopen("nunta.out","w");for(int i=c.v[0];i>0;--i)fprintf(fout,"%d",c.v[i]);return 0;}