#include <bits/stdc++.h>
using namespace std;
FILE *f=fopen("nunta.in","r");
FILE *g=fopen("nunta.out","w");
int nr1[211],nr2[211],nr3[211],n;
void fibb(int poz){
    if(poz==n+1){
        for(int i=nr2[0];i>=1;i--)fprintf(g,"%d",nr2[i]);
    }
    else{
        int nrcif=max(nr1[0],nr2[0]),t=0;
        for(int i=1;i<=nrcif;i++){
            nr3[i]=nr1[i]+nr2[i]+t;
            t=0;
            if(nr3[i]>9){
                nr3[i]=nr3[i]%10;
                t=1;
            }
        }
        nr3[0]=nrcif;
        if(t){
                nr3[nrcif+1]=1;
                nr3[0]++;
        }
        for(int i=0;i<=nr3[0];i++){
            nr1[i]=nr2[i];
            nr2[i]=nr3[i];
        }
        fibb(poz+1);
    }
}
int main()
{
    nr1[1]=1;
    nr2[1]=2;
    nr1[0]=1;
    nr2[0]=1;
    fscanf(f,"%hd",&n);
    if(n<=2)fprintf(g,"%d",n);
    else
        {fibb(3);}

    return 0;
}