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 <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <vector>
#include <cstdlib>
#include <list>
#define _USE_MATH_DEFINES
#include <math.h>

using namespace std;

int main() {

	int n;
	int F[44];
	cin >> n;

	F[0] = 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<algorithm>
using namespace std;

int main(){
  
  int n, fib[50] = {1, 1};
  
  for(int i = 2;i < 45;i++) fib[i] = fib[i - 1] + fib[i - 2];
  
  cin >> n;
  cout << fib[n] << endl;
  
  return 0;
}

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


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

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

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

int F[100]; int N;

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

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

long F[45] = {};

void calcfib(){
	for (long i = 0; i < 45; i++){
		if (i == 0 || i == 1) F[i] = 1;
		else F[i] = F[i - 1] + F[i - 2];
	}
}

int main(){
	long n;
	cin >> n;
	calcfib();
	cout << F[n] << endl;
	return 0;
}

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

int main()
{
 int n; cin>>n;
 vector<ll> fib(n + 1);
 fib.at(0) = 1;
 fib.at(1) = 1;
 for (int i = 2; i <= n; i++)
 {
   fib.at(i) = fib.at(i - 1) + fib.at(i - 2);
 }
 cout << fib.at(n) << endl;

}

C++: #include<algorithm>
#include<climits>
#include<cmath>
#include<iomanip>
#include<iostream>
#include<list>
#include<map>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<utility>
#include<vector>

#define lint long long
#define REP(i, x, n) for(int i = x ; i < n ; i++)
#define rep(i, n) REP(i, 0, n)
#define repr(i, n) for(int i = n - 1 ; i >= 0 ; i--)
#define SORT(c) sort((c).begin(), (c).end())
#define SORT_INV(c) sort((c).begin(), (c).end(), greater<int>())
#define IINF INT_MAX
#define LLINF LLONG_MAX

using namespace std;

lint fib[50] = {0};

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

C++: #define scanf_s scanf
#include <iostream>
using namespace std;
int F[46] = { 0 };
int fib(int n) 
{
	if (n >= 0) {
		if (n <= 1) { return F[n] = 1; }
		if (F[n] != 0) {
			return F[n];
		}
		return F[n] = fib(n - 1) + fib(n - 2);
	}
}
int main(void)
{
	int n;
	scanf_s("%d", &n);
	printf("%d\n", fib(n));
}

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

static const int maxn=44;

int DP[45];

int Fibonacci(int n) {
  if (n==0 or n==1) {
    return DP[n]=1;
  }
  if (DP[n]!=(-1)) {
    return DP[n];
  }
  return DP[n]=Fibonacci(n-1)+Fibonacci(n-2);
}
int main() {
  std::ios::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  memset(DP,(-1),sizeof(DP));
  Fibonacci(maxn);
  int n;
  cin>>n;
  cout<<DP[n]<<endl;
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < n; i++)
typedef long long ll;


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

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

C++: #include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < n; ++i)
#define REPR(i, n) for (int i = n - 1; i >= 0; --i)
#define FOR(i, a, b) for (int i = a; i < b; ++i)
#define FORR(i, a, b) for (int i = b - 1; i >= a; --i)
#define SORT(v) sort(v.begin(), v.end())
#define SORTR(v) sort(v.rbegin(), v.rend())
#define REV(v) reverse(v.begin(), v.end())
#define ITER(itr, v) for (auto itr = v.begin(); itr != v.end(); ++itr)
#define LB(v, x) (lower_bound(v.begin(), v.end(), x) - v.begin())
#define UB(v, x) (upper_bound(v.begin(), v.end(), x) - v.begin())
#define SZ(v) (int)v.size()
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;
	vector<ll> fib(n + 1);
	fib[0] = 1;
	fib[1] = 1;
	FOR(i, 2, n + 1) {
		fib[i] = fib[i - 1] + fib[i - 2];
	}
	cout << fib[n] << endl;

	return 0;
}

C++: #include <iostream>
#include <array>
#include <algorithm>
#include <vector>
#include <bitset>
#include <set>
#include <unordered_set>
#include <cmath>
#include <complex>
#include <deque>
#include <iterator>
#include <numeric>
#include <map>
#include <unordered_map>
#include <queue>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <limits>
#include <iomanip>
#include <functional>
#include <cassert>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define rep(i, k, n) for (ll i=k; i<(ll)n; ++i)
#define REP(i, n) rep(i, 0, n)
#define ALL(v) v.begin(),v.end()
template < class T > inline bool chmax(T& a, T b) {if (a < b) { a=b; return true; } return false; }
template < class T > inline bool chmin(T& a, T b) {if (a > b) { a=b; return true; } return false; }
#define DEBUG_VLL(vec) REP(sz, vec.size()) std::cerr<<vec[sz]<<(sz==vec.size()-1?'\n':' ');

const long long MOD = 1000000007;
const long long HIGHINF = (long long)1e18;
const int INF = (int)1e9;

ll n;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n;
    vll fib(n + 1, 1);
    for (ll i = 2; i <= n; i++) fib[i] = fib[i - 2] + fib[i - 1];
    cout << fib[n] << '\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 dp[45];
  dp[0] = 1;
  dp[1] = 1;
  for (int i=2 ; i <= n; i++){
    dp[i] = dp[i-1]+dp[i-2];
  }
  return dp[n];
}

C++: #include <iostream>

using namespace std;

int solve(int n)
{
    int sum[3] = {1, 1, 1};
    if (n < 2)
        return 1;
    for (int i = 1; i < n; i++)
    {
        sum[2] = sum[1] + sum[0];
        sum[0] = sum[1];
        sum[1] = sum[2];
    }
    return sum[2];
}

int main()
{
    int n;
    scanf("%d", &n);
    printf("%d\n", solve(n));
}