Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	fmt.Println(resolve(parseProblem()))
}

func parseProblem() int {
	return scanInt(sc)
}

func resolve(n int) int {
	dp := make([]int, n+1)
	dp[0], dp[1] = 1, 1
	for i := 2; i <= n; i++ {
		dp[i] = dp[i-1] + dp[i-2]
	}
	return dp[n]
}

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <bits/stdc++.h>
#include <tuple>

#define REP(i, n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
const int INF = 1e9;

using namespace std;
int calc[45];

int fib(int n){
    if(calc[n] != 0)
        return calc[n];
    for(int i = 2; i <= n; i++)
        calc[i] = calc[i-2] + calc[i-1];
    return calc[n];
}

int main() {
    int n;
    cin >> n;
    REP(i, 45) calc[i] = 0;
    calc[0] = 1;
    calc[1] = 1;
    cout << fib(n) << endl;
    return 0;
}

C++: import std.algorithm;
import std.array;
import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;

/// n 番目のフィボナッチ数を求める
/// F(0) = 0, F(1] = 1, F(2) = 1, F(3) = 2, F(4) = 3
int fib(int n) {
    if (n == 0) return 0;

    auto mat = new Mat2x2([[1, 1], [1, 0]]);
    auto m = mat.pow(n, int.max);
    return m.get(0, 1);
}

void main() {
    int n = readint;
    // 問題文の定義だとF(0) = 1, F(1) = 1 なので値を 1 だけずらす
    writeln(fib(n + 1));
}

class Mat2x2 {
    private const N = 2;
    private const int[][] _mat;

    this(const int[][] init) {
        assert(init.length == N);
        assert(init[0].length == init[1].length && init[0].length == N);

        _mat = init.dup;
    }

    int get(int r, int c) const {
        return _mat[r][c];
    }

    Mat2x2 mul(const Mat2x2 m, int mod) const {
        auto t = new int[][](N, N);

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                int x = 0;
                for (int k = 0; k < N; k++) {
                    x = (x + (_mat[i][k] * m.get(k, j)) % mod) % mod;
                }
                t[i][j] = x;
            }
        }
        return new Mat2x2(t);
    }

    Mat2x2 copy() const {
        return new Mat2x2(_mat);
    }

    Mat2x2 pow(int k, int mod) const {
        assert(k > 0);
        if (k == 1) return this.copy();

        auto m = this.pow(k / 2, mod);
        return k % 2 == 0
            ? m.mul(m, mod)
            : this.mul(m.mul(m, mod), mod);
    }

    void dump() const {
        writeln(_mat[0][0], " ", _mat[0][1]);
        writeln(_mat[1][0], " ", _mat[1][1]);
    }
}

C++: #include <iostream>

using namespace std;


int F[44];

int main() {
  F[0] = 1;
  F[1] = 1;
  for (int i = 2; i < 44; ++i) {
    F[i] = F[i-1] + F[i-2];
  }

  int input;
  cin >> input;
  cout << F[input]<< endl;
}

C++: #define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

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

int main(){
  
  int n;
  cin>>n;
  
  vector<int> dp(45);
  dp[0]=dp[1]=1;
  
  for(int i=2;i<=44;i++){
    dp[i]=dp[i-1]+dp[i-2];
  }
  
  cout<<dp[n]<<endl;
      
  return 0;
}

C++: #include <iostream>

using namespace std;


int main()
{
    long fib[45];
    int n;
    cin >> 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;
}

C++: #include <iostream>
#include <string>
#include <map>
#include <set>
using namespace std;
#define MAX 100000

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 <iostream>

using namespace std;

int fib(int n);

int main() {
    int n;
    int dp[45];

    //?????????
    /* ??????3-1 */
    dp[0]=1;
    /* ??????3-2 */
    dp[1]=1;
    //??\???
    cin >> n;

    //DP
    for (int i = 2; i <= n; i++) {
        /* ??????3-3 */
      d@[i]=dp[i-1]+dp[i-2];
    }

    //??????
    cout << dp[n] << endl;

    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<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define mp make_pair
const int inf=1e9+7;
const ll mod=1e9+7;

int DP[45];

void fibonacci(int n){
    if(DP[n-1]==0){
        fibonacci(n-1);
    }
    if(DP[n-2]==0){
        fibonacci(n-2);
    }
    DP[n] = DP[n-1] + DP[n-2];
}

int main() {
    int n;
    cin>>n;
    DP[0] = 1;
    DP[1] = 1;
    if(n>=2){
        fibonacci(n);
    }
    cout<<DP[n]<<endl;
}

C++: #include <iostream>
using namespace std;
long long dp[45];

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

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

C++: #include <iostream>

int F[45] = {1, 1};

int fib_recurse(int n) {
    if (n < 2) {
        return 1;
    }
    return fib_recurse(n - 1) + fib_recurse(n - 2);
}

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

int fib_dp(int n) {
    if(n < 2) {
        return F[n];
    }
    for (int i = 2; i <= n; i++) {
        F[n] = F[i - 1] + F[i - 2];
    }
}

int main() {
    int n;
    std::cin >> n;
    std::cout << fib_memo(n) << std::endl;
    return 0;
}

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

template <class T> struct Matrix {
  vector<vector<T>> value;
  T init;

  Matrix(vector<vector<T>> vec,T init_) :init(init_), value(vec) {}
  Matrix(int h, int w, T init_) : init(init_) , value(h, vector<T>(w,init_)) {}

  Matrix<T> operator*(Matrix<T>& left) {
      Matrix<T> res(value.size(),left[0].size(),init);
      for(int i = 0;i < value.size();i++){
          for(int k = 0;k < left.size();k++){
              for(int j = 0;j < left[0].size();j++){
                  res[i][j] = (res[i][j] + value[i][k] * left[k][j]);
              }
          }
      }
      return res;
  }

  vector<T>& operator[](int n){
      return value[n];
  }

  size_t size(){
      return value.size();
  }

  Matrix<T> operator^(long long n){
      Matrix<T> a = *this;
      Matrix<T> res(a.size(),a.size(),init);
      for(int i = 0;i < a.size();i++){
          res[i][i] = 1;
      }

      while(n > 0){
          if(n & 1) res = res * a;
          a = a * a;
          n >>= 1;
      }
      return res;
  }
};



int main(){
    int n;
    cin >> n;
    Matrix<int> a({{1,1},{1,0}},0);
    cout << (a ^ (n + 1))[1][0] << endl;
}

C++: #include <iostream>
using namespace std;
int F[100];
int main() 
{
int n;
F[0] = 1;
F[1] = 1;
for (int i=2; i<45; ++i) 
{ // ???????????????
F[i] = F[i-2]+F[i-1];
}
cin>>n;
cout<<F[n]<<endl;
}