#include <iostream>
#include <cstdio>
#include <fstream>
using namespace std;

int n=2;



int main()
{   int kk;
    /*FILE *f=fopen("kfib.in","r");
    fscanf(f,"%d",&kk);
    fclose(f);*/
    freopen("kfib.in","r",stdin);
    freopen("kfib.out","w",stdout);
cin>>kk;
   unsigned  long long v[3][3],v2[3][3],vr[3][3];

vr[1][1]=1;
vr[1][2]=1;
vr[2][1]=1;
vr[2][2]=0;
v2[1][1]=1;
v2[1][2]=1;
v2[2][1]=1;
v2[2][2]=0;

int ii=1;
    for(ii=1;ii<kk;ii++)
    {
        v[1][1]=vr[1][1];
        v[1][2]=vr[1][2];
        v[2][1]=vr[2][1];
        v[2][2]=vr[2][2];





 for(int i=1;i<=n;i++)
   for(int j=1;j<=n;j++)
    { vr[i][j]=0;

     for(int k=1;k<=n;k++)
            vr[i][j]+=v[i][k]*v2[k][j];
    }

   }


cout<<v[1][1];

    /*f=fopen("kfib.out","w");
    fprintf(f,"%ud",v[1][1]);*/
    return 0;
}