Go: package main

import "fmt"

func main() {
	var n int
	fmt.Scan(&n)

	x, y := int64(0), int64(1)
	for i := 0; i < n; i++ {
		x, y = y, x+y
	}

	fmt.Println(x)
}

C++: #include <iostream>
using namespace std;
long long fibo(int n){
    int F[n];
    F[0] = F[1] = 1;
	for(int i = 2; i <= n; i++)
        F[i] = F[i-1]+F[i-2];
	return F[n];
}

int main(void){
    int n;
	cin >> n;
	cout << fibo(n) << endl;
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int dp[50];

int fib(int n){
  if (n == 0 || n == 1) {
    return dp[n] = 1;
  }
  else if (dp[n] != -1) {
    return dp[n];
  }
  else {
  return dp[n] = fib(n - 1) + fib(n - 2);
  }
}

int main() {
  int n, i;
  cin >> n;
  for (i = 0; i < 50; i++) {
    dp[i] = -1;
  }
  
  scanf("%d", &n);
  printf("%d\n", fib(n));
  
  return 0;

}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(n); ++i)
#define repr(i, a, b) for (int i=a; i<(b); ++i)
#define reprev(i, n) for (int i=n-1; i>=0; --i)
#define reprrev(i, a, b) for (int i=b-1; i>=(a); --i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main() {
    cout << fixed << setprecision(10);
    
    int n; cin >> n;
    vector<int> fib(n+1);
    fib[0] = 1; fib[1] = 1;
    repr(i, 2, n+1) {
        fib[i] = fib[i-2] + fib[i-1];
    }
    cout << fib[n] << endl;
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
int dx[4] = {1, 0, 0, -1};
int dy[4] = {0, 1, -1, 0};

int main(void){
	int n; cin >> n;
	int dp[100];
	dp[0] = dp[1] = 1;
	reps(i, 2, n + 1){
		dp[i] = dp[i - 1] + dp[i - 2];
	}

	cout << dp[n] << endl;
	return 0;
}

C++: #include <iostream>

using namespace std;

int main() {
  int n;
  int dp[45];

  // 初期化
  dp[0] = 1;
  dp[1] = 1;

  //入力
  cin >> n;

  // DP
  for(int i = 2; i <= n; i++) dp[i] = dp[i-1] + dp[i-2];

  // 出力
  cout << dp[n] << endl;

  return 0;
}

C++: #include<iostream>
using namespace std;

int main()
{
  int n; cin >> n ;
  int F[50];
  F[0] = F[1] = 1;
  for (int i = 2 ; i <= n; ++i)
  {
    F[i] = F[i-1] + F[i-2];
  }

  cout << F[n] << endl;

  return 0;
}

C++: #include <iostream>
#include <vector>

using namespace std;

int fib(int);

vector<int> num;

int main(){
    int n;
    cin >> n;
    
    num.resize(n, 0);
    
    cout << fib(n) << endl;
}

int fib(int n){
    if(n == 0 || n == 1){
        return 1;
    }
    
    if(num[n] != 0){
        return num[n];
    }
    
    num[n] = fib(n - 1) + fib(n - 2);
    return num[n];
}

C++: #include <iostream>

int fib(int n){
   if ( n == 1 || n == 0){
        return 1;
   }
   return fib(n-1) + fib(n - 2);
}

int fib = 0;
std::cin>>fib;
std::cout<<fib(n)<<std::endl;

C++: #include<bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
typedef long long ll;
#define rep(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define REP(i,num,n) for(int i=num, i##_len=(n); i<i##_len; ++i)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
#define print(x) (cout << (x) << endl)
#define pb push_back
#define mp make_pair
#define sz(x) int(x.size())
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class itr> void cins(itr first, itr last){ for(auto i = first; i != last; i++){ cin >> (*i); } }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++) ans += to_string(*i) + " "; if(!ans.empty()) ans.pop_back(); cout << ans << endl; }
#define fs first
#define sc second

const int INF = 1e9;
const ll LLINF = 1e16;
const ll MOD = 1e9+7;
template<class T> inline void add(T &a, T b){a = ((a+b) % MOD + MOD) % MOD;};

template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}
 
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
 
template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value!=0>::type
fill_v(U &u,const V... v){u=U(v...);}
 
template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value==0>::type
fill_v(U &u,const V... v){
  for(auto &e:u) fill_v<T>(e,v...);
}
 

// 指定した文字cが文字列に何文字入ってるか
ll stringcount(string s, char c) {
    return count(s.cbegin(), s.cend(), c);
}


// 割り算の切り上げ処理
template<typename T>
T rp(T a, T b) {
  return (a + b - 1) / b;
}

// 桁和
template<typename T>
T digsum(T n) {
    T res = 0;
    while(n > 0) {
        res += n%10;
        n /= 10;
    }
    return res;
}

// 回文判定
bool kai (string s) {
    string t{s};
    reverse(begin(t), end(t));
    return s == t;
}

using pint = pair<int, int>;
using pll = pair<ll, ll>;

int main(void)
{
    cout.tie(0);
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    ll n;
    cin >> n;
    vector<ll> dp(55);
    dp[0] = 1;
    dp[1] = 1;
    REP(i, 2, n + 1){
        dp[i] = dp[i - 1] + dp[i - 2];
    }
    print(dp[n]);
}