Go: package main

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

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()
	n := nint()
	r := fibonacci(n)
	fmt.Println(r)
}

func fibonacci(n int) int{
	if n == 0 || n == 1{
		return 1
	}else{
		fiList := make([]int, n+1)
		fiList[0] = 1
		fiList[1] = 1
		for i:=2; i<n+1; i++{
			fiList[i] = fiList[i-1] + fiList[i-2]
		}
		return fiList[n]

	}

}

func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef pair<ll,ll> Pll;
typedef pair<string,string> Pstring;
typedef pair<double,double> Pdouble;



#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define Precision13 cout << fixed << setprecision(13)
const double PI=3.14159265358979323846;
const int MAX = 510000;
const int MOD = 1000000007;
const int INF = 1<<29;

using Graph = vector<vector<char>>;

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

C++: #include <cstdint>

using namespace std;

#define MEMO_SIZE 44
int64_t memo[MEMO_SIZE];

void fib_init()
{
  for (uint32_t i = 0; i < MEMO_SIZE; i++) {
    memo[i] = -1;
  }
}

uint32_t fib(uint32_t i)
{
  if (i == 0) {
    return memo[0] = 1;
  } else if (i == 1) {
    return memo[1] = 1;
  } else {
    int64_t val1 = memo[i - 1], val2 = memo[i - 2];
    if (val1 == -1) {
      val1 = memo[i - 1] = fib(i - 1);
    }

    if (val2 == -1) {
      val2 = memo[i - 2] = fib(i - 2);
    }

    return val1 + val2;
  }
}

#include <iostream>

int32_t main()
{
  fib_init();
  uint32_t i;
  cin >> i;
  cout << fib(i) << endl;
  return 0;
}

C++: #include<iostream>
using namespace std;
int main(void){
	int n;
	cin>>n;
	int fib[n];
	fib[0]=fib[1]=1;
	for(int i=2;i<=n;i++)fib[i]=fib[i-1]+fib[i-2];
	cout<<fib[n]<<endl;;
	return 0;
}

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

int n;
int F[45];
int fibo(int i) {
    if (F[i]) {
        return F[i];
    }
    return fibo(i - 1) + fibo(i-2);
}

int main() {
    cin >> n;
    F[0] = F[1] = 1;
    cout << fibo(n);

    return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <cmath>
#include <ctype.h>
#include <string>
#include <sstream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>

using namespace std;

int main()
{
    int fib[45] = {};
    fib[0] = fib[1] = 1;

    int n;
    cin >> n;
    if (n < 2) {
        cout << fib[n];
    } else {
        for (int i = 2; i <= n; i++) {
            fib[i] = fib[i - 1] + fib[i - 2];
        }
        cout << fib[n] << endl;
    }

    return 0;
}

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

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

C++: #include<stdio.h>
#define MAX 44

int main(){
  int n, i; 
  int F[50];

  scanf("%d", &n);
  if(n>MAX){
    printf("Number must be smaller than 44!\n");
    return -1;
  }
  
  F[0] = F[1] = 1;
  for ( i = 2; i <= n; i++ ){
    F[i] = F[i-1] + F[i-2];
  }

  printf("%d\n", F[n]);

  return 0;
}

C++: #include<iostream>

using namespace std;

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

  int F[50];

  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<bits/stdc++.h>
using namespace std;

int f[50];

int fibo(int n)
{
  if(n <= 1) return 1;
  else{
    if(f[n]){
      return f[n];
    }
    else{
      return f[n] = fibo(n-1)+fibo(n-2);
    }
  }
}

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

  cout << fibo(n) << endl;
  return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<stdlib.h>
#include<cstdio>
int fib(int);
using namespace std;
int main()
{
	int n,ans;
	cin >> n;
	ans = fib(n - 1);
	cout << ans << endl;
}
int fib(int n)
{
	if (n < 1)
		return 1;
	else
	{
		return fib(n - 1)+fib(n - 2);
	}
}

C++: // #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define Graph vector<vector<int>>
typedef long long ll;
typedef pair<int, int> P;
const int INF = 1000000007;

int main(){
    int N;
    cin >> N;
    vector<int> A(50);
    A[0] = A[1] = 1;
    for(int i = 2; i <= N; i++){
        A[i] = A[i - 1] + A[i - 2];
    }
    cout << A[N] << endl;
}

C++: #include <iostream>

using namespace std;

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

    int a = 1, b = 1;
    if (n < 2) {
        cout << 1 << endl;
    } else {
        int ans;
        for (int i = 2; i <= n; ++i) {
            ans = a + b;
            b = a;
            a = ans;
        }

        cout << ans << endl;
    }

    return 0;
}

C++: // 
#include <bits/stdc++.h>
#define endl "\n"
#define _GLIBCXX_DEBUG //配列外参照エラー表示,gcc依存
#define rep(i,n) for(int i=0;i<int(n);i++)
#define SZ(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ipair;
template <class T>ostream &operator<<(ostream &o,const vector<T>&v)
{o<<"{";for(int i=0;i<(int)v.size();i++)o<<(i>0?", ":"")<<v[i];o<<"}";return o;}
namespace you {
    std::string to_string(char val) {
        return std::string(1, val);
        // return std::string{val};
        // you::to_string(char)
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(12);

    int n;
    vector<int> dp(50);
    cin>>n;
    dp[0]=1,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, a, b) for (int i = a; i < (b); i++)
#define rrep(i, a, b) for (int i = a; i >= (b); i--)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
using P = pair<int, int>;
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;
}
void hr() {
   cerr << "--------------" << endl;
}
const int INF = 1001001001;
const int MOD = 1000000007;
// const int MOD = 998244353;
int memo[100];
int f(int n) {
   if (memo[n] != 0) return memo[n];
   if (n == 0 || n == 1) return 1;
   return memo[n] = f(n - 1) + f(n - 2);
}
int main() {
   cin.tie(0);
   ios_base::sync_with_stdio(0);

   int n;
   cin >> n;
   int ans = f(n);
   cout << ans << endl;
   return 0;
}