//
//  main.cpp
//  B
//
//  Created by 黄宇凡 on 16/5/14.
//  Copyright © 2016年 黄宇凡. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>

using namespace std;

const int maxn = 205;


struct bignum{
    string x;
    int d[55];
    int len;
    bignum(){
        memset(d,0,sizeof(d));
        len = 0;
    }
    void read(){
        cin >> x;
        len = (int)x.length();
        for(int i = 0;i < len;i++){
            d[i] = x[len - 1 - i] - '0';
        }
    }
    bool operator < (const bignum& rhs)const{
        if(len < rhs.len) return true;
        for(int i = len - 1;i >= 0;i--){
            if(d[i] < rhs.d[i]) return true;
            else if(d[i] > rhs.d[i]) return false;
        }
        return false;
    }
    bignum operator + (const bignum & rhs) const{
        int l = max(rhs.len,len);
        bignum x;
        for(int i = 0;i < l;i++){
            x.d[i] += (d[i] + rhs.d[i]);
            x.d[i + 1] += x.d[i] / 10;
            x.d[i] = x.d[i] % 10;
        }
        if(x.d[l] > 0) x.len = l + 1;
        else x.len = l;
        return x;
    }
    void print(){
        for(int i = len - 1;i >= 0;i--){
            printf("%d",d[i]);
        }
        puts("");
    }
}a[maxn];


int main(int argc, const char * argv[]) {
    a[0].len = 1;
    a[0].d[0] = 1;
    a[1].len = 1;
    a[1].d[0] = 1;
    for(int i = 2;i <= 200;i++){
        a[i] = a[i - 1] + a[i - 2];
    }
    int n;
    while(scanf("%d",&n) != EOF){
        a[n].print();
    }
    return 0;
}