Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

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

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list {
		buf.Write([]byte(fmt.Sprintf(" %d", v)))
	}
	buf.Write([]byte("\n"))
	buf.Flush()
}

//solve
//単純な場合
func fibonacci_(n int) int {
	if n == 0 || n == 1 {
		return 1
	}
	return fibonacci_(n-2) + fibonacci_(n-1)
}

//メモ再帰の利用
func fibonacci(n int) int {
	if n == 0 || n == 1 {
		F[n] = 1
	}
	//F[n]が計算済みの場合
	if F[n] > 0 {
		return F[n]
	}
	F[n] = fibonacci(n-2) + fibonacci(n-1)
	return F[n]
}

const MAX = 50

var F [MAX]int

func main() {
	sc.Split(bufio.ScanWords)
	n := nextInt()
	fmt.Println(fibonacci(n))

}

C++: #include <bits/stdc++.h>
#include <math.h>
#include <vector>
#include <queue>
#include <iomanip>
#include <string>
#include <algorithm>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep_1 (i,j,n) for(int i=j;i<n;i++)
typedef long long ll;
typedef long l;
const ll l_INF = 1010101010101010;
const int INF = 1010101010;
const int dx[] = {-1,0,1,0,-1,-1,1,1};
const int dy[] = {0,-1,0,1,1,-1,1,-1};

int main(){
  int n; cin>>n;
  int dp[10101010];
  rep(i,10101010){
    if(i==0||i==1) dp[i]=1;
    else dp[i]=dp[i-1]+dp[i-2];
  }
  cout<<dp[n]<<endl;
}

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

int main()
{
    int n;
    scanf("%d", &n);
    vector<int> a(n + 1);
    a[0] = a[1] = 1;
    for (int i = 2; i <= n; i++)
    {
        a[i] = a[i - 1] + a[i - 2];
    }
    printf("%d\n", a[n]);
}

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

#define MAX 50

int dp[MAX];

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

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

  cout << fib(n) << endl;

  return 0;
}

C++: #include <stdio.h>
int F[50];
int fib(int n) {
	if (n == 0 || n == 1) {
		return F[n]=1;
	}
	if (F[n] != -1) return F[n];
	return F[n]=fib(n - 1) + fib(n - 2);
}
int main(void) {
	int n,i=50;
	while (i--) F[i]=-1;
	scanf("%d", &n);
	printf("%d\n",fib(n));
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <queue>
#include <stack>
#include <string>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>

#define rep(i, n) for(int i = 0; i < n; i ++)
#define ALL(T) T.begin(), T.end()
#define mp make_pair
#define pb push_back

using namespace std;

typedef pair<int, int> pii;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<string> vs;

const int INF = 1 << 24;

int fib(int);

int main(void){
    int n;
    cout << fib(n) << endl;

    return 0;
}

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

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<list>
#include<string>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
using namespace std;

const int NIL = -1;
const int MAX = 2000001;

int main(void)
{
	int n;
	int F[45];
	F[0] = F[1] = 1;
	cin >> n;
	for (int i = 2; i <= n; i++)
		F[i] = F[i - 1] + F[i - 2];
	cout << F[n] << endl;
	return 0;
}

C++: #include<bits/stdc++.h>
#include<vector>
#include<list>
#include<stack>
#include<queue>
#include<algorithm>
using namespace std;

int sol(int x){
    int a=1,b=1;
    for(int i=0;i<x;i++){
        int tmp=a;
        a=a+b;
        b=tmp;
    }
    return b;
}

int main(){
    int n;
    long long s;
    scanf("%d",&n);
    s=sol(n);
    printf("%d\n",s);
    return 0;
}

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

int main() {

    int F[44];

    int n;

    cin >> n;

    F[0] = 1;
    F[1] = 1;
    for(int i = 2; i <= n; i++) {
        F[i] = F[i-1] + F[i-2];
        //cout << "n = " << i << " " << F[i] << endl;
    }

    cout << F[n] << endl;

    return 0;
}

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

int main() {
    int n;
    std::cin >> n;
    std::vector<int> vec(n+1, 0);
    vec[0] = 1;
    vec[1] = 1;
    for (int i = 2; i <= n; i++) {
        vec[i] = vec[i-1] + vec[i-2];
    }
    std::cout << vec[n] << std::endl;
}

C++: #include <iostream>

using namespace std;

int A[128];
int fib(int n){
  A[0] =1;
  for(int i=1;i<44;++i){
    A[i] =A[i-1];
    if(i>1)A[i]+=A[i-2];
  }
  return A[n-1];

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

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;
}