Go: package main

import "fmt"

func fibonacci() func() int {
	x, y := 0, 1
	return func() int {
		x, y = y, x+y
		return x
	}
}
func main() {
	var n int

	fmt.Scan(&n)
	f := fibonacci()
	for i := 0; i < n; i++ {
		f()
	}
	fmt.Println(f())
}

C++: #include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string>
#include <stdlib.h>
#include <queue>
#include <stack>
#include <utility>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define ll long long
#define INF 1000000001
#define mod 1000000007
using namespace std;

int main(){
	//cin.tie(0);
	//ios::sync_with_stdio(false);

	int n;
	cin>>n;
	vector<ll> a(n+1);
	a[0]=1;
	a[1]=1;
	rep(i,n-1){
		a[i+2]=a[i+1]+a[i];
	}
	cout<<a[n]<<endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
int main(){
  int n;
  cin >> n;
  vector<long long> fib(n + 1, 1);
  for (int i = 2; i <= n; i++){
    fib[i] = fib[i - 1] + fib[i - 2];
  }
  cout << fib[n] << endl;
}

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

const int N = 44;
int dp[N] = {};
int n;

int rec(int x)
{
	if(x == 0 || x == 1){
		dp[x] = 1;
		return dp[x];
	}
	
	if(dp[x] != 0)
		return dp[x];
	
	return dp[x] = rec(x - 1) + rec(x - 2);
}

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	cin >> n;
	
	cout << rec(n) << endl;
	
	return 0;
}

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

const int MAX = 100;
long long dp[MAX];

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

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

C++: #include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using pii = pair<int, int>;

int main() {
	int n;
	cin >> n;
	vector<int> dp(n + 1);
	dp[0] = dp[1] = 1;
	for (int i = 1; i < n; i++) {
		dp[i + 1] = dp[i] + dp[i - 1];
	}
	cout << dp[n] << endl;
	return 0;
}

C++: #ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#endif

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#endif




#define int long long
#define rng(i,l,r) for(size_t i=(l);i<(r);++i)
#define rep(i,n) rng(i,0,n)
#define gnr(i,l,r) for(size_t i=(r)-1;i>=(l);i--)
#define per(i,b) gnr(i,0,b)
#define ALL(obj) (obj).begin(), (obj).end()   //1,2,3,...
#define rALL(obj) (obj).rbegin(), (obj).rend()//...,3,2,1

using namespace std;
//using ll = long long;


const int MOD = 1000000007;
const int INF = 1e18;

const int dx4[4] = {1, 0, -1, 0};
const int dy4[4] = {0, 1, 0, -1};
const int dx8[8] = {1,1,0,-1,-1,-1,0,1};
const int dy8[8] = {0,1,1,1,0,-1,-1,-1};

const double pi = acos(-1);



template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }


using Graph = vector<vector<int>>;
int gcd(int a,int b){return b?gcd(b,a%b):a;}
//*max_element(ALL(vector))
//count(ALL(vector),num) -> n




void solve(){
    
    // remove the bottom 3 lines when you submit this code.
    std::ifstream in("sample.txt");
    std::cin.rdbuf(in.rdbuf());

    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int n; cin >> n;
    vector<int> fib(100);
    for (int i = 0; i < 100; i++) {
        
        if(i<=1) fib[i] = 1;
        else{
            fib[i] = fib[i-1] + fib[i-2];
        }
    }
    cout << fib[n] << endl;
}



signed main() {
    solve();
    return 0;
}

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

vector<int> fibonatti;
long long int  dp[10000];
int calc(int n){
  if(n <= 1) return 1;
  if(dp[n] != -1)return dp[n];
  fibonatti[n] = calc(n - 1) + calc(n - 2);
  return dp[n] = fibonatti[n];
}

int main(int argc, char *argv[]){
  int n;
  cin >> n;
  fibonatti.resize(n);
  fibonatti[0] = fibonatti[1] = 1;
  for (int i = 0; i <= n; i++) {
    dp[i] = -1;
  }
  dp[0] = dp[1] = 1;
  std::cout << calc(n) << std::endl;
  return 0;
}

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

int Fibonatch(int result[], int num)
{
    int ret = result[num];

    if (ret == 0) {
        if (num > 1) {
            ret = Fibonatch(result, num - 1) + Fibonatch(result, num - 2);
        }
        else {
            ret = 1;
        }
        result[num] = ret;
    }

    return ret;
}

int main(void)
{
    int num;
    int ret[45] = {0};
    int result;

    scanf("%d", &num);
    result = Fibonatch(ret, num);

    printf("%d\n", result);

    return 0;
}

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

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

int main(){
  int n; cin>>n;
  cout<<fib(n)<<endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n - 1); i >= 0; i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define get_unique(x) x.erase(unique(all(x)), x.end());
typedef long long ll;
typedef complex<double> Complex;
const int INF = 1e9;
const ll MOD = 1e9 + 7;
const ll LINF = 1e18;
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;
}
template <class T>
vector<T> make_vec(size_t a) {
    return vector<T>(a);
}
template <class T, class... Ts>
auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}
int main() {
    int n;
    cin >> n;
    vector<ll> fib(1000);
    fib[0] = fib[1] = 1;
    rep(i, 50) fib[i + 2] = fib[i + 1] + fib[i];
    cout << fib[n] << endl;
}

C++: //递归求第n个斐波那契数列
#include<iostream>
using namespace std;

int F[50];
//记忆化递归生成斐波那契数列 
/*int fibonacci(int n)
{
	if(n==1||n==2)
		return F[n]=1;
	if(F[n])
		return F[n];
	else return F[n]=fibonacci(n-1)+fibonacci(n-2);
}*/
//动态规划法生成斐波那契数列
/*
int fibonacci(int n)
{
	if(n==0||n==1)
		F[n]=1;
	for(int i=2;i<n;i++)
	{
		F[i]=F[i-1]+F[i-2];		
	}	
} */
int main()
{
	int n;
	cin>>n;
	F[0]=F[1]=1;
	for(int i=2;i<=n;i++)
	{
		F[i]=F[i-1]+F[i-2];		
	}
	//int result=fibonacci(n);
	cout<<F[n]<<endl;
	return 0;
}