Go: package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
)

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	fmt.Println(resolve(parseProblem()))
}

func parseProblem() int {
	return scanInt(sc)
}

func resolve(n int) int {
	dp := make([]int, n+1)
	dp[0], dp[1] = 1, 1
	for i := 2; i <= n; i++ {
		dp[i] = dp[i-1] + dp[i-2]
	}
	return dp[n]
}

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++:                                         #include <bits/stdc++.h>
                                        #include<iostream>
                                        #include<cstdio>
                                        #include<vector>
                                        #include<queue>
                                        #include<map>
                                        #include<cstring>
                                        #include<string>
                                        #include <math.h>
                                        #include<algorithm>
                                    //    #include <boost/multiprecision/cpp_int.hpp>
                                        #include<functional>
                                #define int long long
                                        #define inf  1000000007
                                        #define pa pair<int,int>
                                        #define ll long long
                                        #define pal pair<double,pa>
                                        #define ppa pair<int,int>
                                        #define ppap pair<pa,pa>
                                        #define ssa pair<string,int>
                                        #define  mp make_pair
                                        #define  pb push_back
                                        #define EPS (1e-10)
                                        #define equals(a,b) (fabs((a)-(b))<EPS)
                                  #define VI vector<int>
                                        using namespace std;


int gcd(int a,int b){
	if(a<b) return gcd(b,a);
	if(b==0) return a;
	if(a%b==0) return b;
	return gcd(b,a%b);
}
map<int,int>ma;
           signed main(){
               int n;
 // cin>>n;
         int f[100];
           	f[0]=1;
           	f[1]=1;
           	for(int  i=2;i<50;i++)f[i]=f[i-1]+f[i-2];
           	int u;
           	cin>>u;
           	
           	cout<<f[u]<<endl;
           }

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

int rec_fibonacci(int n, std::map<int, int>* m) {
  if (n == 0 || n == 1)
    return 1;
  if (m->find(n) == m->end())
    (*m)[n] = rec_fibonacci(n-1, m) + rec_fibonacci(n-2, m);
  return (*m)[n];
}

int fibonacci(int n) {
  std::map<int, int> m;
  return rec_fibonacci(n, &m);
}

int main() {
  int n;
  std::cin >> n;
  std::cout << fibonacci(n) << std::endl;
}

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

using namespace std;
vector<int> fib(50);

int makefib(int n){
  if(n==0||n==1) return fib[n]=1;
  if(fib[n]!=-1) return fib[n];
  else return fib[n]=makefib(n-1)+makefib(n-2);
}
		  
int a;
int main(void){
  cin>>a;
  for (int i=0; i<50; i++) fib[i]=-1;
  cout<<makefib(a)<<endl;
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long ll;
typedef pair<int,int>P;
int dp[100];
int fibo(int x){
	if(x==0||x==1){return dp[x]=1;}
	if(dp[x]!=0){return dp[x];}  
  	return dp[x]=fibo(x-1)+fibo(x-2);
  
}
 


int main() {
 rep(i,100){dp[i]=0;}
  int n; cin>>n;
	cout<<fibo(n)<<endl;
  
  
}

C++: #include<iostream>

using namespace std;

long fivo(long a){
  if (a==1 or a==2) return 1L;

  else 
    
    return fivo(a-1)+fivo(a-2);
}




int main(){
  long n,req;
  
  cin >>req;
  n=fivo(req+1);
  //  for(n=1;n<=20;n++){
  //cout<<fivo(n)<<endl;
  // }
  cout <<n<<endl;
  return 0;
}

C++: #include <bits/stdc++.h>
//#include <boost/multiprecision/cpp_int.hpp>
using namespace std;
//using namespace boost::multiprecision;
typedef long long int ll;
typedef long double ld;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const long long INF = 1LL << 60;
bool pairCompare(const pair<double,ll>& firstElof, const pair<double,ll>& secondElof){
    return firstElof.first < secondElof.first;
}
bool pairCompareSecond(const pair<double,ll>& firstElof, const pair<double,ll>& secondElof){
    return firstElof.second < secondElof.second;
}
#define MAX_N 100100
#define MOD 998244353
// 四方向への移動ベクトル
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
ll gcd(ll a,ll b) {return b ? gcd(b,a%b):a;}
ll lcm(ll c,ll d){return c/gcd(c,d)*d;}
ll ans[100];
ll fib(ll x){
    if (ans[x]!=-1)return ans[x];
    ans[x]=fib(x-1)+fib(x-2);
    return ans[x];
}

int main(){
    fill(ans,ans+50,-1);
    ans[0]=1;
    ans[0]=1;
    ll n;
    cin >> n;
    cout << fib(n) << endl;
    return 0;
}