Go: package main

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

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

// func main(){
// 	sc := bufio.NewScanner(os.Stdin)
// 	sc.Scan()
// 	n, _ := strconv.Atoi(sc.Text())
// 	fmt.Println(fib(n))
// }

import (
	"fmt"
)

func main(){
	var n, pre1, pre2, now int
	fmt.Scan(&n)
	if n == 0 || n == 1{
		fmt.Println(1)
	} else {
		pre1, pre2 = 1, 1
		for i:=1; i<n; i++{
			now = pre1 + pre2
			pre2 = pre1
			pre1 = now
		}
		fmt.Println(now)
	}

}

C++: #include <iostream>
#include <stdio.h>
#include <vector>
#include <utility>
#include <string>
#include <algorithm>
#include <cmath>
#include <queue>
#include <cstring>
 
typedef long long ll;

#define rep(i,n) for(ll i = 0; i < n; i++)
 
using namespace std;
 
const ll INF = ll(1e18)+1;
const double PI=3.14159265358979323846;

int dp[50];

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

C++: #include <iostream>
#include <vector>
using namespace std;
int fib(int x, vector<int>& f)
{
if (f[x-1] == -1) f[x-1] = fib(x-1, f);
if (f[x-2] == -1) f[x-2] = fib(x-2, f);
return f[x-1] + f[x-2];
}

int main()
{
int x; cin >> x;
vector<int> f(x+1, -1); f[0] = f[1] = 1;
cout << fib(x, f) << endl;
return 0;
}

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

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

    int first = 1;
    int second = 1;
    
    for (int i = 2; i < input; ++i) {
        int third = first + second;
        first = second;
        second = third;
    }
    cout << second << "\n";
    
    return 0;
}

C++: class RecursiveFibonacci:public Fibonacci{
public:
	virtual int calc(int x);
};

int RecursiveFibonacci::calc(int x){
	if(x == 0){
		return 0;
	}else if(x == 1){
		return 1;
	}else{
		return calc(x - 1) + calc(x - 2);
	}
}

C++: using namespace std;

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

    int first = 1;
    int second = 1;
    
    for (int i = 2; i < input; ++i) {
        int third = first + second;
        first = second;
        second = thid;
    }
    cout << second;
    
    return 0;
}

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

int fib(int n);

int main(){
	int n;
	cin >> n;
	cout << fib(n) << endl;
}
	
int fib(int n){
	int num1 = 1,num2 = 1;
	int temp = 0;
	if(n == 0 || n == 1) return 1;
	
	for (int i = 1;i < n;i++){
		temp = num2;
		num2 = num1 + num2;
		num1 = temp;
	}
		return num2;
}

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

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

	return 0;

}

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

int main(){
    int n;
    cin >> n;
    vector<long long> dp(n+1);
    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 <bits/stdc++.h>
using namespace std;

#define NIL -1

int dp[100];

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

int main(){
    int n;
    cin >> n;
    for(int i=0; i<100; i++){
        dp[i] = NIL;
    }
    dp[0] = 1;
    dp[1] = 1;
    for(int i=0; i<n; i++){
        fib(i);
    }
    cout << fib(n) << endl;
}

C++: fibonacci :: Int -> Int
fibonacci = fibo (1, 1) 2
    where
      fibo :: (Int, Int) -> Int -> Int -> Int
      fibo (pp, prev) pos n
          | n < 2 = 1
          | pos >= n = pp + prev
          | otherwise = fibo (prev, pp+prev) (pos+1) n

main :: IO ()
main = do
  n <- readLn
  putStrLn $ show $ fibonacci n

C++: #include <stdio.h>

int dp[50];

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

int main()
{
    int n, i;
    for (i = 0; i < 50; i++)
        dp[i] = -1;

    scanf("%d", &n);
    printf("%d\n", fib(n));

    return 0;
}

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

int F[45];

int fib(int x)
{
	if (F[x]) return F[x];
	if (x <= 1) return F[x] = 1;
	return F[x] = fib(x - 1) + fib(x - 2);
}

int main()
{
	int x;
	scanf("%d", &x);

	printf("%d\n", fib(x));

	return 0;
}

C++: #include<algorithm>
#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
#define MAX 45
int F[MAX];


int fibonacci(int i){
    if(i == 1 || i == 0) return F[i] = 1;
    if(F[i]) return F[i];
    return F[i] = fibonacci(i-1) + fibonacci(i-2);
}

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

    cout << F[n] << endl;

    return 0;
}

C++: #include<iostream>
#include<vector>
using namespace std;
vector<int> memo;
int fib(int n){
    if(n==1||n==0){
        return 1;
    }
    if(memo[n]==-1){
        memo[n] = fib(n - 1) + fib(n - 2);
    }
    return memo[n];
}


int main(){
    int n ;
    cin >> n;
    memo = vector<int>(n + 1, -1);
    cout << fib(n)<<endl;
}

C++: #include<bits/stdc++.h> 
using namespace std;
using ll=long long;
typedef pair<int,int> P;
#define all(v) (v).begin(),v.end()
#define fi first
#define se second
const ll inf=(1e18);
const ll mod=1000000007;
ll dp[100];
ll fib(int n){
    if(n<2){
        return dp[n];
    }
    if(dp[n]!=-1)return dp[n];
    ll res=fib(n-1)+fib(n-2);
    return dp[n]=res;

}
int main(){
int n;
cin>>n;
fill(dp,dp+100,-1);
dp[0]=0;dp[1]=1;
cout<<fib(n+1)<<endl;

}

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

int n, d[50];

long long int fib(long long int k){
	if (!k || k == 1) return 1;
	if (!d[k]) { 
		d[k] = fib(k - 1) + fib(k - 2);
		return d[k];
	}
	else return d[k];
}

int main(){
	cin >> n;
	d[0] = 1; d[1] = 1;
	cout << fib(n) << endl;
}

C++: //#include <bits/stdc++.h>
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <map>
#include <iomanip>
#include <stdlib.h>
#include <stdio.h>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <time.h>
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef pair<int, int> Pii;
typedef pair<int, ll> Pil;
typedef pair<ll, ll> Pll;
typedef pair<ll, int> Pli;

#define fi first
#define se second
#define mp make_pair
 
const ll MOD = 1e9 + 7;
const ll MOD2 = 998244353;
const ll INF = 1ll << 60;
const double PI = 2 * asin(1);

void yes() {printf("yes\n");}
void no() {printf("no\n");}
void Yes() {printf("Yes\n");}
void No() {printf("No\n");}
void YES() {printf("YES\n");}
void NO() {printf("NO\n");}

ll Fib[45];

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

  return 0;
}