Go: package main

import (
	"fmt"
)

const MAX = 45

var dp [MAX]int

func fin(n int) int {
	if dp[n] != 0 {
		return dp[n]
	}

	switch n {
	case 0:
		dp[n] = 1
	case 1:
		dp[n] = 1
	default:
		dp[n] = fin(n-1) + fin(n-2)
	}
	return dp[n]
}

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

C++: #include <iostream>
#include <stdlib.h>
 
using namespace std;
 
#define MAX_N 44

class Fib{
private:
  int size;
  int *A;
public:
  Fib(int size){
    this->size = size;
    makeFib();
  }

  int getFib(int n){
    return A[n];
  }

  void makeFib(){
    int i;
    this->A = (int*)malloc(sizeof(int)*this->size);
    this->A[0] = 1;
    this->A[1] = 1;
    for(i = 2;i < sizeof(this->A);i++){
      this->A[i] = this->A[i-2]+this->A[i-1];
    }
  }

  ~Fib(){
    free(A);
  }
};
 
int main(){
 
    int n;
    Fib *fib = new Fib(MAX_N); 

    cin >> n;
 
    cout << fib->getFib(n) << endl;
 
    delete fib;

    return 0;
}

C++: #include <stdio.h>
#include <vector>
#include <list>
#include <map>
#include <array>
#include <memory>
#include <string>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
#include <unordered_map>
#include <stdexcept>


using std::string;
using std::vector;


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// util
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

std::vector<std::string> split(const std::string& input, char delimiter)
{
    std::istringstream stream(input);

    std::string field;
    std::vector<std::string> result;
    while (std::getline(stream, field, delimiter)) {
        result.push_back(field);
    }
    return result;
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// user func
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void printList(const vector<int>& list) {
    // print
    for(int i = 0; i < list.size(); i++){
        printf(" %d", list[i]);
    }
    printf("\n");
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// logic
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
vector<int> memo(45, -1);
int fib(int n){
    if(memo[n] != -1) return memo[n];

    if(n == 0) return 1;
    if(n == 1) return 1;
    int res = fib(n-1) + fib(n-2);
    memo[n] = res;
    return res;
}
void solve() {
    int n;
    scanf("%d", &n);
    printf("%d\n", fib(n));
}


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// main
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int main() {
    solve();
    return 0;
}

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

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define whole(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define bit(n) (1LL<<(n))
// functions
template <typename T> void unique(T& c){c.erase(std::unique(c.begin(), c.end()), c.end());}
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(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << "(" << p.first << ", " << p.second << ")"; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << "(" << itr->first << ", " << itr->second << ")"; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << "(" << itr->first << ", " << itr->second << ")"; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(nullptr); cout << fixed << setprecision(20);}
} fast_io_;

ll memo[101];
ll fib(int i){
  if(memo[i] > 0)return memo[i];
  if(i <= 1)return memo[i] = 1;
  return memo[i] = fib(i-1) + fib(i-2);
}

int main(int argc, char const* argv[])
{
  int n; cin >> n;
  cout << fib(n) << endl;
  return 0;
}

C++: // input: aldsalds1_10_a.in
#include<iostream>
#define MAX_N 44
#define NIL -1
using namespace std;

int dp[MAX_N];

int fib(int n) {
  if(n == 0 || n == 1)
    return 1;

  if(dp[n] != NIL)
    return dp[n];

  return fib(n-1) + fib(n-2);
}

int main() {
  for(int i=0; i<MAX_N; i++)
    dp[i] = NIL;

  int x;
  cin >> x;

  cout << fib(x) << endl;
}

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



int main() {
    int N;
    cin >> N;

    ll fib[N+1];
    fib[0] = 1;
    fib[1] = 1;

    for (int i=2; i<=N; i++) fib[i] = fib[i-1] + fib[i-2];

    cout << fib[N] << endl;

    return 0;
}

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

long long n;
vector<long long> f;

long long calc(long long x) {
  if(f[x] != -1) return f[x];
  return f[x] = calc(x - 1) + calc(x - 2);
}

int main() {
  cin >> n;
  f.assign(n + 1, -1);
  f[0] = f[1] = 1;
  cout << calc(n) << endl;
  return 0;
}

C++: #include<iostream>
#include <string>
using namespace std;
int a,ans[46];
int main(){
	cin>>a;
	ans[0]=1,ans[1]=2;
	for(int i=0;i<a;i++){
	ans[i+2]=ans[i+1]+ans[i];}
	cout<<ans[a-1]<<endl;
		    return 0;
	}

C++: #include <iostream>
 
using namespace std;
 
typedef unsigned long long ull;
 
auto fib(ull const n) -> ull
{
    return ( n == 1 || n == 0 ) ? n : fib( n - 1 ) + fib( n - 2 );
}
 
int main()
{
    ull n;
    cin >> n;
    cout << fib( n ) << endl;
}