Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

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

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	dp := make([]int, N+1)
	dp[0] = 1
	dp[1] = 1
	for i := 2; i <= N; i++ {
		dp[i] = dp[i-1] + dp[i-2]
	}

	fmt.Fprintln(wtr, dp[N])
	wtr.Flush()
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define _USE_MATH_DEFINES
#include <math.h>
#define rep(i,n) for(int i = 0;i < n;i++)
#define NIL = -1;

ll gcd(long long a,long long b) {
    if (a < b) swap(a,b);
    if (b == 0) return a;
    
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    a / gcd(a,b) * b;
}
const ll mod = 1e9 + 7;

int dx[4] = {0,1,0,-1};
int dy[4] = {1,0,-1,0};

const ll INF = 1e9;
/////////////////////////////////////////////////////////////////////////////////////////

int main(){
    int n;
    cin >> n;
    int 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<iostream>
using namespace std;
int main ()
{
	int fif[100];
	int n,i;
	fif[0]=1,fif[1]=1;
	cin >> n;
	for(i=2;i<=n;i++)
	{
		fif[i]=fif[i-2]+fif[i-1];
	}
	cout << fif[n] << endl;
	return 0;
}

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

using namespace std;
typedef long long int ll;

int dh[4] = {1,0,-1,0};
int dw[4] = {0,1,0,-1};

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

C++: #include <algorithm>
#include <cmath>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
using namespace std;
const int INT_INF = 500000000;
const long long LONG_LONG_INF = (long long)pow(10, 18);
const int MOD = pow(10, 9) + 7;
/* contest template */
int n;
long long fib[45];

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

C++: #include<bits/stdc++.h>
using namespace std;
int fibo(int n){
  if(n==0||n==1)return 1;
  return fibo(n-1)+fibo(n-2);
}
int main(){
  int n;
  cin >> n;
  cout << fibo(n) << endl;
  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];
    }

    return 0;
}

C++: #include <iostream>

using namespace std;

int fibo[45];

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

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

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long ll;
typedef pair<int, int> P;
ll dp[55];
int main() {
  int n;
  cin >> n;
  dp[0] = 1;
  dp[1] = 1;
  for (int i = 2; i < 50; i++) {
    dp[i] = dp[i - 1] + dp[i - 2];
  }
  cout << dp[n] << endl;
}

C++: //
//  main.cpp
//  fibonacci_number
//
//  Created by ???????????? on 2017/10/17.
//  Copyright ?? 2017 ????????????. All rights reserved.
//

#include <iostream>
#include <stdio.h>

using namespace std;

int main(int argc, const char * argv[]) {
    int n;
    scanf("%d", &n);
    int A[n];
    A[0]=A[1]=1;
    for(int i = 2; i <= n; i++ ){
        A[i] = A[i-2]+A[i-1];
    }
    cout << A[n] <<endl;;
    return 0;
}