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<iostream>

using namespace std;
int fib(int n);

int memo[45];
int main(){
  int n;
  cin >> n;
  cout << fib(n) << endl;
  retrun 0;
}

int bib(int n){

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

  }

C++: #include <iostream>
#include <unordered_map>
using namespace std;
int fib(int);
unordered_map<int, int> memoFib;

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

int fib(int n) {
  if(memoFib.count(n)) return memoFib[n];
  int a;
  a = memoFib[n] = n == 0 || n == 1 ? 1 : fib(n - 1) + fib(n - 2);
  return a;
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<algorithm>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<deque>
#include<queue>
#include<map>
#include<set>
#define ll long long
#define vll vector<ll>
#define dou(s) atof(s.c_str())
#define lon(s) atoll(s.c_str())
#define str(n) to_string(n)
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,b,a) for(ll i=b;i>=a;i--)
#define ALL(a) a.begin(),a.end()
#define rALL(a) a.rbegin(),a.rend()
#define line "\n"
#define mav(a) (*max_element(ALL(a)))
#define miv(a) (*min_element(ALL(a)))
#define vfind(a,n) (find(ALL(a),n)-a.begin())
#define prque priority_queue
#define MOD 1000000007ll
using namespace std;
void solve();
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	solve();
}

//nCk(mod p)
/*ll fac[510000], finv[510000], inv[510000];
void cmodf(ll p = MOD) {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	rep(i, 2, 510000) {
		fac[i] = fac[i - 1] * i%p;
		inv[i] = p - inv[p%i] * (p / i) % p;
		finv[i] = finv[i - 1] * inv[i] % p;
	}
}
ll cmod(ll n, ll k, ll p = MOD) {
	return fac[n] * (finv[k] * finv[n - k] % p) % p;
}*/

//最大公約数
ll gcd(ll n, ll m) {
	ll k = n % m;
	while (k != 0) { n = m; m = k; k = n % m; }
	return m;
}
ll gcd(vector<ll> a) {
	rep(i, 1, a.size()) {
		ll k = a[i - 1] % a[i];
		while (k != 0) {
			a[i - 1] = a[i];
			a[i] = k;
			k = a[i - 1] % a[i];
		}
	}
	return a.back();
}

//最小公倍数
ll lcm(ll n, ll m) {
	ll t = n * m, k = n % m;
	while (k != 0) { n = m; m = k; k = n % m; }
	return t / m;
}
ll lcm(vector<ll> a) {
	ll n;
	rep(i, 1, a.size()) {
		n = a[i - 1] * a[i];
		ll k = a[i - 1] % a[i];
		while (k != 0) {
			a[i - 1] = a[i];
			a[i] = k;
			k = a[i - 1] % a[i];
		}
		n /= a[i];
		a[i] = n;
	}
	return n;
}

//keyの小さい方から探していった時に初めてvalueがjoken以上になる時のkey（keyが増えたらvalueも増えるか同じになるとき）
ll value(ll key) {
	/*変更*/
	return 0;
}
ll mini(ll lkey, ll rkey/*ここも調べる*/, ll joken) {
	ll mkey;
	while (lkey != rkey) {
		mkey = (lkey + rkey) / 2;
		if (value(mkey) >= joken)rkey = mkey;
		else lkey = mkey + 1;
	}
	return rkey;
}

//ペア配列の整理
struct pea { ll n, m; };
void msort(vector<pea> &a, bool k = true) {
	struct hikakukansu {
		static bool unstable(const pea &x, const pea &y) { return x.m < y.m; }
		static bool stable(const pea &x, const pea &y) { return (x.m == y.m ? x.n < y.n : x.m < y.m); }
	};
	if (k)sort(ALL(a), hikakukansu::unstable);
	else sort(ALL(a), hikakukansu::stable);
}

//変数定義

//再帰関数

//アルゴリズム
void solve() {
	ll n; cin >> n;
	vll a(n+1,1);
	rep(i, 2, n+1)a[i] = a[i - 1] + a[i - 2];
	cout << a[n] << line;
}

C++: #include <iostream>

using namespace std;
int F[100];
int main() {
	int n;
	cin >> n;
	F[0] = 1;
	F[1] = 1;
	for (int i=2; i<=n; ++i) {
		F[i] = F[i-2] + F[i-1];
	}
	cout << F[n] << endl;
}

C++: #include<iostream>
#include<vector>
#define NIL -1
using namespace std;

int fib(vector<int>& F, int n){
    if (F[n] != NIL) return F[n];
    return F[n] = fib(F, n - 1) + fib(F, n - 2);
}

int main(){
    int n;
    cin >> n;
    vector<int> F(n + 1, NIL);
    F[0] = F[1] = 1;
    cout << fib(F, n) << endl;
    return 0;
}

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

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

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

int fib(int n);

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

    return 0;
}

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

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


using namespace std;


int main()
{
	int n;
	int a[45] = { 1,1 };
	ios::sync_with_stdio(false);

	cin >> n;

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

	cout << a[n] << endl;

	return 0;

}

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

int FibonacciNumber(int n) {

	if (n <= 1) {
		return 1;
	}
	return FibonacciNumber(n - 1) + FibonacciNumber(n - 2);
}

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

	cout << FibonacciNumber(n) <<endl;
	
}

C++: #include<cstdio>

const int maxn = 44 + 1;
int a[maxn];

int calcFibonacciNumber(int n) {
    if (n < 0) {
        return 0;
    }
    if (n == 0 || n == 1) {
        return 1;
    }
    if (a[n] != -1) {
        return a[n];
    }
    a[n] = calcFibonacciNumber(n - 1) + calcFibonacciNumber(n - 2);
    return a[n];
}

int getFibonacciNumber(int n) {
    return calcFibonacciNumber(n);
}

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