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 <iostream>

using namespace std;

int fib(int n);

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

dp[0] = 1;
dp[1] = 1;

cin >> n;

for(int i = 2; i <= n; i++) {
dp[i] = dp[i-1] + dp[i-2];
}

cout << dp[n] << dp << endl;
return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <cmath>
#include <numeric>
#include <iomanip>


#define log(x) cout<<x<<endl
#define pb push_back
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(),(x).end()
typedef long long lint;
using namespace std;

int gcd(lint x, lint y){
  return y==0 ? x:gcd(y,x % y);
}


int digsum(int n) {
  int res = 0;
  while(n > 0) {
    res += n%10;
    n /= 10;
  }
  return res;
}


int dignum(int n) {
  int res = 0;
  while(n > 0) {
    res++;
    n /= 10;
  }
  return res;
}


int stringcount(string s, char c) {
  return count(s.cbegin(), s.cend(), c);
}


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


int combi(int n, int r){
  int num = 1;
  for(int i = 1; i <= r; i++){
    num = num * (n - i + 1) / i;
  }
  return num;
}


int main(){
  lint n;
  vector<lint> l;
  cin>>n;
  l.pb(1);
  l.pb(1);
  for(lint i=2;i<=n;i++) l.pb(l[i-1]+l[i-2]);
  cout<<l[n]<<endl;
}