Go: package main

/*
フィボナッチ数列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func fibWithMemo(n int, memo map[int]int) int {
	if n == 0 || n == 1 {
		return 1
	}
	if val, ok := memo[n]; ok {
		return val
	}
	memo[n] = fibWithMemo(n-1, memo) + fibWithMemo(n-2, memo)
	return memo[n]
}

func fib(n int) int {
	memo := make(map[int]int)
	return fibWithMemo(n, memo)
}

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	fmt.Println(fib(n))
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include <stdio.h>

using namespace std;

long long Fibonacci[43] = {0};

long long fibo(int n){
	if(n == 0)	return 1;
	else if(n == 1)	return 1;
	else{
		if(Fibonacci[n-1] != 0 && Fibonacci[n-2] != 0){
			//Do nothing
		}else if(Fibonacci[n-1] != 0){
			Fibonacci[n-2] = fibo(n-2);
		}else if(Fibonacci[n-2] != 0){
			Fibonacci[n-1] = fibo(n-1);
		}else{
			Fibonacci[n-1] = fibo(n-1);
			Fibonacci[n-2] = fibo(n-2);
		}
		return Fibonacci[n-1] + Fibonacci[n-2];
	}
}

int main(){
	int n;
	scanf("%d",&n);
	printf("%lld\n",fibo(n));
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int (i) = 0;(i) < (n);(i)++)
#define SORT(c) sort((c).begin(),(c).end())
#define MOD 1000000007 //S(vector).size()
using namespace std;
typedef long long ll;

int dp[50];

int main(void){
	int n;
	cin >> n;

	dp[0] = 1;
	dp[1] = 1;
	for(int i = 2; i <= n; i++)	dp[i] = dp[i - 1] + dp[i - 2];
	
	cout << dp[n] << endl;
	return 0;
}

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

int main(){
    int n;
    cin>>n;
    int sum[n+1];
    for(int i=0;i<=n;i++){
        if(i==0||i==1){
            sum[i]=1;
        }
        else{
            sum[i]=sum[i-1]+sum[i-2];
        }
    }
    cout<<sum[n]<<endl;
    return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef vector<vector<int> > vvi;
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<string, int> psi;
typedef pair<int, int> pii;
#define rep(i,n) for(int i = 0; i < (n); i++)
#define loop(i) for(int i = 0;true; i++)
#define all(x) (x).begin(), (x).end()
#define mn 1000000007
int main() {
	int N;
	cin >> N;
	int num = 1;
	vi A;
	loop(i) {
		if (N+1==i) {
			cout<<A[A.size()-1]<<endl;
			break;
		}
		if (i >= 2) {
			A.push_back(A[i-1]+A[i-2]);
		}
		else {
			A.push_back(1);
		}
	}
};

C++: //ALDS1_10_A:Fibonacci Number
#include <bits/stdc++.h>
using namespace std;
#define LL_MIN -9223372036854775808
#define LL_MAX 9223372036854775807

int main(){
    int n;
    cin >> n;
    int fib[44];
    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;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
#define rep(i,n) for(ll i=0;i<(n);i++)
#define repr(i,n) for(ll i=(n-1);i>=0;i--)
#define pb push_back
#define mp make_pair
#define all(x) x.begin(),x.end()
#define br cout << "\n";
using namespace std;
const int INF = 1e9;
const int MOD = 1e9+7;
using Graph = vector<vector<ll>>;
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;}

// 0 false, 1 true 
// string to int : -48
// ceil(a)  1.2->2.0
// c++17	g++ -std=c++17 a.cpp


int main() {
    std::cout << std::fixed << std::setprecision(15);
    long long n;
    cin >> n;

    ll dp[50];

    dp[0] = 1;
    dp[1] = 1;

    rep(i,n){
        if(i == 0){
            continue;
        }
        dp[i+1] = dp[i] + dp[i-1];
    }

    cout << dp[n] << endl;

}

C++: #include<iostream>

using namespace std;

int dp[45] = {1,1};
int fibo(int n){
  if(dp[n] != 0) return dp[n];
  dp[n] = fibo(n-1) + fibo(n-2);
  return dp[n];
}

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