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 <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>

using namespace std;

using ll = long long;

#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define REPD(i,n) for(ll i=n-1;i>=0;i--)
#define FOR(i,a,b) for(ll i=a;i<=(ll)(b);i++)
#define FORD(i,a,b) for(ll i=a;i>=(ll)(b);i--)

#define input(...) __VA_ARGS__; in(__VA_ARGS__)

template<class T>
void print(vector<T> a) {
  cout << "[ ";
  REP(i, a.size()) cout << a[i] << " ";
  cout << "]" << endl;
}

void print() {
  std::cout << std::endl;
}

template <class Head, class... Tail>
void print(Head&& head, Tail&&... tail) {
  std::cout << head << " ";
  print(std::forward<Tail>(tail)...);
}

void in() { }

template <class Head, class... Tail>
void in(Head&& head, Tail&&... tail) {
  cin >> head;
  in(std::forward<Tail>(tail)...);
}

vector<ll> table(100, -1);
ll fibo(ll n) {
  if (n <= 1) return 1;
  if (table[n] != -1) return table[n];
  return table[n] = fibo(n - 1) + fibo(n - 2);
}

int main() {
  ll input(n);
  cout << fibo(n) << endl;
}

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

int main() {
	int n[1000000], s, i;
	n[0] = 0;
	n[1] = 0;
	n[2] = 1;

	cin >> s;

	for (i = 0; i < s; i++) {
		n[3 + i] = n[i] + n[i + 1] + n[i + 2];
	}

	cout << n[s - 1] << endl;

	return 0;
}

C++: #include <iostream>

using namespace std;


int fibonacci(int n)
{
	int preFib = 1;
	int prepreFib = 1;
	int fib;

	if (n <= 1) {
		return 1;
	}

	for (int i = 2; i <= n; i++) {
		fib = preFib + prepreFib;
		prepreFib = preFib;
		preFib = fib;
	}

	return fib;

}

int main(void)
{
	int n;
	cin >> n;
	cout << fibonacci(n);

	return 0;
}

C++: #include <stdio.h>

fi(int a) {
  return (a == 0 || a == 1) ? 1 : fi(a - 1) + fi(a - 2);
}

int main(void) {
  int n;
  scanf("%d", &n);
  printf("%d\n", fi(n));
  return 0;
}

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

int Fib(int n){
	double phi = (1+sqrt(5))/2;
	return floor(pow(phi,n)/sqrt(5) + 0.5 );
}

int main() {
	int n;
	
	while(cin>>n){
		cout<<Fib(n+1)<<endl;
	}
	
	
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <utility>

using namespace std;

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

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)

int main() {
    int n, dp[50];
    cin >> n;
    dp[0] = 1;
    dp[1] = 1;
    FOR(i, 2, n + 1) dp[i] = dp[i - 1] + dp[i - 2];
    cout << dp[n] << endl;
    return 0;
}

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

using namespace std;
typedef long long ll;
typedef long int li;
typedef long double lb;
#define rep(i,j,n) for (ll i = j; i < (n); i++)
#define repr(i,j,n) for(ll i = j; i >= (n); i--)
#define all(x) (x).begin(),(x).end()
#define CLR(mat,f) memset(mat, f, sizeof(mat))
#define IN(a, b, x) (a<=x&&x<b)
#define out(ans) cout << ans << endl
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; }
typedef pair<ll,ll>P;
const ll mod=1e9+7;
const ll INF = 1LL<<60;
const ll m=1LL<<32;

int main(){

  ll n;cin>>n;
  ll fib[50];
  fib[0]=fib[1]=1;
  rep(i,2,50){
    fib[i]=fib[i-1]+fib[i-2];
  }

  out(fib[n]);

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;

ll memo[55];

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

int main() {
    fib(50);
    int n;
    cin >> n;
    cout << memo[n] << endl;
}

C++: #include<cstdio>
#include<cstdlib>
#include<iostream>
using namespace std;
int main() {
  int n;
  int dp[44] = {};
  cin >> n;
  dp[1] = dp[0] = 1;

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

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


int fibonacci(int n) {
    int fib[50];
    fib[0] = fib[1] = 1;
    
    for (int i = 2; i <= n; i++) {
        fib[i] = fib[i-1] + fib[i-2];
    }

    return fib[n];
}

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

    cout << fibonacci(n) <<endl;

    return 0;
}

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

int main(){
    int n; cin >> n;
    int dp[44] = {1,1};
    for(int i=2; i<n; ++i){
        dp[i] = dp[i-1] + dp[i-2];
    }
    cout << dp[n-1] << endl;
}

C++: #include <iostream>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define NIL -1
#define MAX 10000

int dp[50];


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

int main()
{
    int n;
    rep(i, 50) dp[i] = -1;

    cin >> n;
    cout << fibonacci(n) << endl;

    return 0;
}

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

void make_fib(vector<int>& fib){
  for(int i=2; i<fib.size(); i++){
    fib[i] = fib[i-1] + fib[i-2];
  }
}

int main(){
  vector<int> fib(50,1);
  make_fib(fib);
  int n; cin >> n;
  cout << fib[n] << "\n";
}

C++: #include <cstdio>

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

int
main ()
{
    int n;
    int dp[50];
    for (int i=0; i<50; i++) dp[i] = -1;
    scanf("%d", &n);
    printf("%d\n", fibo(n, dp));
    return 0;
}