Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	dp := make([]int, N+1)
	dp[0] = 1
	dp[1] = 1
	for i := 2; i <= N; i++ {
		dp[i] = dp[i-1] + dp[i-2]
	}

	fmt.Fprintln(wtr, dp[N])
	wtr.Flush()
}

C++: #include <bits/stdc++.h>

using namespace std;

#define FOR(i,s,e) for((i)=(s);(i)<(int)(e);(i)++)
#define REP(i,e) FOR(i,0,e)

#define all(o) (o).begin(), (o).end()
#define psb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))

typedef long long ll;
typedef pair<int, int> PII;

const double EPS = 1e-10;

const int N = 44;
int n;
int memo[N+1];

//?????????TLE?§£???
//?¨?????????????????????§2^44 - (?????????)

int fib(int k) {
  if (memo[k]) return memo[k];
  return fib(k-1) + fib(k-2);
}

int dp(int k) {
  memset(memo, 0, sizeof(memo));
  if (k<=1) return 1;
  memo[0] = memo[1] = 1;
  for (int i=2; i<=k; i++)
    memo[i] = memo[i-1] + memo[i-2];
  return memo[k];
}

int main() {
//  memset(memo, 0, sizeof(memo));
//  memo[0] = memo[1] = 1;
  scanf("%d ", &n);
//  printf("%d\n", fib(n));
  printf("%d\n", dp(n));

	return 0;
}

C++: #include<iostream>

using namespace std;

int fib(int n);

int main() {
  int n;

  //入力
  cin >> n;

  //出力
  cout << fib(n) << endl;

  return 0;
}

int fib(int n){
  int memo[1000] = {0};
  if(n==0 || n == 1){
    return 1;
  }else if(memo[n] != 0){
    return memo[n];
  }else{
    return memo[n] = memo[n-1] + memo[n-2];
  }
}

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

const int MAX = 44;
int F[MAX];

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


int main() {
    ios::sync_with_stdio(false);

    F[0] = F[1] = 1;
    for(int i=2; i<=MAX; i++) F[i] = -1;

    int n;
    cin >> n;
    cout << fib(n) << endl;
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ll long long
ll fib(ll  n)
{
  ll f[100000];
  ll i;
  f[0] = 1;
  f[1] = 1;
  for (i = 2; i <= n; i++)
      f[i] = f[i-1] + f[i-2];

  return f[n];
}
int main(){
    ll i,j,k,l,n,m;
    cin>>m;
    cout<<fib(m)<<endl;
    return 0;
}

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

using namespace std;

int main(){
    int n;
    scanf("%d", &n);

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

C++: #include <bits/stdc++.h>
#include <cmath>

using namespace std;
#define rep(i, n) for (ll i = 0; i < (n); ++i)
//#define rep(i, n) for (int i = 0; i < (n); ++i)
#define sz(x) ll(x.size())
//typedef long long ll;
typedef long long ll;
//typedef pair<int, int> P;
//typedef pair<ll, ll> P;
//const double INF = 1e10;
const ll INF = 10e15;
const ll MINF = -10e10;
//const int INF = INT_MAX / 100;
#define cmin(x, y) x = min(x, y)
#define cmax(x, y) x = max(x, y)


//ifstream myfile("~/Downloads/02.txt");
//ofstream outfile("log.txt");
//outfile << setw(6) << setfill('0') << prefecture << setw(6) << setfill('0') << rank << endl;
// std::cout << std::bitset<8>(9);

//typedef priority_queue<P, vector<P>, greater<P> > PQ_ASK;
const int mod = 1000000007;
const double PI = 3.14159265358979323846;

typedef pair<string, int> P;


string to_upper(string str) {
    int diff = 'a' - 'A';
    for (int i = 0; i < str.size(); i++) {
        char c = str[i];
        if ('A' <= c && c <= 'Z') {
            c += diff;
            str[i] = c;
        }
    }
    return str;
}


int main() {
    vector<ll> fibonacci(50, 0);
    fibonacci[0] = 1;
    fibonacci[1] = 1;
    for (int i = 2; i < 50; i++) {
        fibonacci[i] = fibonacci[i - 1] + fibonacci[i - 2];
    }

    int n;
    cin >> n;
    cout << fibonacci[n] << endl;

}

C++: #ifdef LOCAL_BUILD
#include "pch.h"
#define DLOG(msg) cout << "#" << __LINE__ << ":" << msg << endl;
#define DLOG_V(var)\
  cout << "#" << __LINE__ << ":" << #var << " : " << var << endl;
#else
#include <bits/stdc++.h>
#define DLOG(msg)
#define DLOG_V(var)
#endif
using namespace std;

uint64_t solve(int n) {
  vector<uint64_t> cache(n + 1, 0);
  cache[0] = cache[1] = 1;
  for (int i = 2; i <= n; ++i) {
    cache[i] = cache[i - 1] + cache[i - 2];
  }
  return cache[n];
}

int main() {
  int n;
  cin >> n;
  uint64_t result = solve(n);
  cout << result << endl;
}

C++: #include<bits/stdc++.h>
using namespace std;
int memo[100];
int fibonacci(int n){
    for(int i = 2; i <= n; i++){
        memo[i] = memo[i -1] + memo[i - 2];
    }
    return memo[n];
}

int main(){
    int n;
    cin >> n;
    memo[0] = 1;
    memo[1] = 1;
    int res = fibonacci(n);
    cout << res << endl;
}

C++: #include <iostream>

using namespace std;

int fib(int n);

int main() {
    int n;

    //??\???
    cin >> n;

    //??????
    cout << fib(n) << endl;

    return 0;
}

int fib(int n){
    /* ??????1 */
    if(n == 0){
        return 1;
    }else if(n == 1){
        return 1;
    }else{
        return fib(n-1) + fib(n-2);
    }
}