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

vector<int> F(45, -1);
int fib(int n) {
  if (F[n] != -1)
    return F[n];
  else if (n == 1 || n == 0) {
    F[n] = 1;
  } else {
    F[n] = fib(n - 1) + fib(n - 2);
  }
  return F[n];
}
int main() {
  int n;
  cin >> n;
  cout << fib(n) << endl;
}

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

typedef long int lint;
typedef long long int llint;
typedef pair<int, int> pii;
typedef pair<int, string> pis;
typedef pair<long, long> pll;

#define EACH(i, c) for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define FOR(i, s, e) for (int i = (s); i < (int)(e); ++i)
#define REP(i, n) FOR(i, 0, n)
#define endl "\n"

const int INF = 100000000;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

template<typename T>
void print(const std::vector<T>& v, char sep=' ') {
  for (int i = 0; i < (int)v.size(); i++) {
    if (i != 0) cout << sep;
    cout << v[i];
  }
  cout << endl;
}

int fib[45];

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  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<cmath>
#include<algorithm>
#include<vector>
#include<queue>

using namespace std;

int main(){

  int n;
  cin >> n;

  int fib[50];
  fib[0]=1,fib[1]=1;

  for(int i=2;i<50;i++){
    fib[i]=fib[i-1]+fib[i-2];
  }

  cout << fib[n] << endl;


}

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

int Fibonacci(int n) {
    int F[45];
    F[0] = 1;
    F[1] = 1;
    for(int i = 2; i <= n; i++) {
        F[i] = F[i-1] + F[i-2];
    }
    return F[n];
}

int main() {
    int n;
    cin >> n;
    cout << Fibonacci(n) << endl;
    return 0;
}

C++: #include <iostream>

using namespace std;

int fib(int n) {
    int a = 1;
    int b = 1;

    int i = 0;
    while (i < n) {
        a = b;
        b = a + b;
        ++i;
    }
    return a;
}

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

    cout << fib(n) << endl;

    return 0;
}

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

int main()
{
int n;cin>>n;//scanf("%d",&n);
int fib[n+1];//vector<int> fib(n+1,1);
for(int i=0;i<n+2;i++)fib[i]=1;
if(n>1){for(int i=2;i<n+2;i++){fib[i]=fib[i-2]+fib[i-1];}}
cout<<fib[n]<<endl;//printf("%d\n",fib[n]);
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<climits>
#include<cmath>
#include<cstdio>
#include<deque>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

int F[45] = {};

int fib(int n) {
	if (n == 0 || n == 1)
		return F[n] = 1;
	else
		return F[n] ? F[n] : F[n] = fib(n - 1) + fib(n - 2);
}

int main() {
	int n;	cin >> n;
	cout << fib(n) << endl;
	return 0;
}

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

int fib(int n){
	int ans[45] = {0,1},i;
	for(i=2;i<=n;i++){
		ans[i] = ans[i-1]+ans[i-2];
	}
	return ans[i];
}

int main() {
	int n;
	cin >> n;
	cout << fib(n) << endl;
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
/*{{{*/  //template
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<29
#define LINF LLONG_MAX/3
#define mp make_pair
#define pb push_back
#define EB emplace_back
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define sz(x) (int)(x).size()
#define debug(x) cerr<<#x<<":"<<x<<endl
#define debug2(x,y) cerr<<#x<<","<<#y":"<<x<<","<<y<<endl
//struct fin{ fin(){ cin.tie(0); ios::sync_with_stdio(false); } } fin_;
struct Double{ double d; explicit Double(double x) : d(x){} };
ostream& operator<<(ostream& os,const Double x){ os << fixed << setprecision(20) << x.d; return os; }
template<typename T> ostream& operator<<(ostream& os,const vector<T>& vec){ os << "["; for(const auto& v : vec){ os << v << ","; } os << "]"; return os; }
template<typename T,typename U> ostream& operator<<(ostream& os,const pair<T,U>& p){ os << "(" << p.first << ","<< p.second <<")"; return os; }
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
ll gcd(ll a,ll b){ if(b==0) return a; else return gcd(b,a%b); }
constexpr double eps = 1e-14; 
constexpr ll mod = 1e9+7;
const int dx[]={1,0,-1,0} ,dy[] = {0,1,0,-1};
/*}}}*/

ll memo[64];

ll fib(int n){
    if(memo[n]!=-1) return memo[n];
    if(n==0 or n==1) return memo[n]=1;

    return memo[n] = fib(n-1) + fib(n-2);
}

int main(){
    rep(i,64) memo[i]=-1;

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

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>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

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

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

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

int Fibonacci(int n){
	if(n==0 || n==1){
		return 1;
	}
	return Fibonacci(n-1) + Fibonacci(n-2);
}

int main() {
	int n;
	cin >> n;
	cout << Fibonacci(n) << endl;
	return 0;
}

C++: #include <iostream>

using namespace std;

int fib(int n);

int main() {
    int n;

    //??\???
    cin >> n;

    //??????
    cout << fib(n) << endl;

    return 0;
}

int fib(int n){
  /* ??????1 */
  if(n==0||n==1)    return 1;
  else if(memo[n]!=0){
    return memo[n];
  }else{
    return memo[n]=fib(n-1)+fib(n-2);
  }
}

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+1; ++i){
        dp[i] = dp[i-2] + dp[i-1];
    }
    cout << dp[n] << endl;
}

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

int dp[50];

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

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

    return 0;
}

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

int main(){
    int A[46];
    int n;
    scanf("%d",&n);
    A[0] = A[1] = 1;
    for(int i=2;i<=n;++i){
        A[i] = A[i-1] + A[i-2];
    }
    printf("%d\n",A[n]);
    return 0;
}

C++: // 

// g++ -std=c++11 abc145_c.cc && ./a.out 
#include <algorithm>
#include <bitset>
#include <cmath>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
using ll = long long;
using P = pair<int,int>;


int memo[50];
int n;

int fibo(int i) {
    if (memo[i] != 0) { return memo[i]; }

    int result = fibo(i - 1) + fibo(i - 2);
    memo[i] = result;
    return result;
}

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

    rep(i, n) memo[i] = 0;
    memo[0] = 1;
    memo[1] = 1;

    cout << fibo(n) << endl;

    return 0;
}