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;
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;
}

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

using ll = long long;
using ld  = long double;
using pll = pair<ll, ll>;
using pld = pair<ld, ld>;
const int INF=1e9+7;
const ll LINF=9223372036854775807;
const ll MOD=1e9+7;
const ld PI=acos(-1);
const ld EPS = 1e-10; //微調整用（EPSより小さいと0と判定など）

int ii() { int x; if (scanf("%d", &x)==1) return x; else return 0; }
long long il() { long long x; if (scanf("%lld", &x)==1) return x; else return 0; }
string is() { string x; cin >> x; return x; }
char ic() { char x; cin >> x; return x; }
void oi(int x) { printf("%d ", x); }
void ol(long long x) { printf("%lld ", x); }
void od_nosp(double x) { printf("%.15f", x); } // 古い問題用
void od(double x) { printf("%.15f ", x); }
// long doubleで受け取り、fをLfなどに変えて出力すると、変な数値が出る
// それをなんとかするには独自の出力を作らなければならなそう
void os(const string &s) { printf("%s ", s.c_str()); }
void oc(const char &c) { printf("%c ", c); }
#define o_map(v){cerr << #v << endl; for(const auto& xxx: v){cout << xxx.first << " " << xxx.second << "\n";}} //動作未確認
void br() { putchar('\n'); }

// #define gcd __gcd //llは受け取らない C++17~のgcdと違うので注意
// int lcm(int a, int b){return a / gcd(a, b) * b;}
#define begin_end(a) a.begin(),a.end() //sort(begin_end(vec));
#define REP(i,m,n) for(ll i=(ll)(m) ; i < (ll)(n) ; i++ )
#define DREP(i,m,n) for(ll i=(ll)(m) ; i > (ll)(n) ; i-- )
#define rep(i,n) REP(i,0,n)
#define m_p(a,b) make_pair(a,b)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
#define p_b push_back
#define SZ(x) ((int)(x).size) //size()がunsignedなのでエラー避けに


// coutによるpairの出力（空白区切り）
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& p) {return s << "(" << p.first << " " << p.second << ")";}
// coutによるvectorの出力（空白区切り）
template<typename T> ostream& operator<<(ostream& s, const vector<T>& v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i]; if (i < len - 1) s << " "; //"\t"に変えるとTabで見やすく区切る
  }
  return s;
}
// coutによる多次元vectorの出力（空白区切り）
template<typename T> ostream& operator<<(ostream& s, const vector< vector<T> >& vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}

//最大値、最小値の更新。更新したor等しければtrueを返す
template<typename T>
bool chmax(T& a, T b){return (a = max(a, b)) == b;}
template<typename T>
bool chmin(T& a, T b){return (a = min(a, b)) == b;}

//4近傍（上下左右） rep(i, 2) にすると右・下だけに進む
vector<int> dx_4 = {1, 0, -1, 0};
vector<int> dy_4 = {0, 1, 0, -1};

// -------- template end - //


// - library ------------- //




// --------- library end - //


int main(){

  ll N = il();

  vector<ll> fib(N+1, 0);
  fib[0] = 1;

  if (N != 0){
    fib[1] = 1;
    REP(i, 2, N+1){
      fib[i] = fib[i-1] + fib[i-2];
    }
  }

  cout << fib[N] << endl;

}

C++: /*
 * ALDS1_10_A.cpp
 *
 *  Created on: May 5, 2018
 *      Author: 13743
 */

#include<iostream>

using namespace std;

int F[44];

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

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

	F[0] = F[1] = 1;

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

C++: #include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
	int n, c=0, m;

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

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

int n;
int _fib[100];

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

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

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

vector<int> vec;
long long cal(int n){
    if(vec[n]!=-1) return vec[n];
    if(n==0) return 0;
    if(n==1) return 1;
    return vec[n]=cal(n-1)+cal(n-2);
}

int main(void){
    int x;
    
    cin >> x;
    x=x+1;
   vec.assign(x+1,-1);
    
    cout << cal(x) <<endl;
}