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++: #define _USE_MATH_DEFINES
#include <iomanip>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <list>
#include <queue>
#include <deque>
#include <algorithm>
#include <numeric>
#include <utility>
#include <complex>
#include <functional>
#include <typeinfo>

#define REP(i, x) for (int i = 0; i < (int)(x); i++)
#define REP1(i, x) for (int i = 1; i <= (int)(x); i++)
#define RREP(i, x) for (int i = ((int)(x)-1); i >= 0; i--)
#define RREP1(i, x) for (int i = ((int)(x)); i > 0; i--)
/*
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

#define all(x) (x).begin(),(x).end()
*/

using namespace std;

int x[100];

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

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    cout << fib(n) << endl;
}

C++: #include <iostream>
using namespace std;
typedef long long ll;
#define MAX 50
ll num[MAX];
int main() {
  int n;
  cin >> n;
  num[0] = num[1] = 1;
  for (int i = 2; i <= n; i++) {
    num[i] = num[i-1] + num[i-2];
  }
  cout << num[n] << endl;
  return 0;
}

C++: 
#include <iostream>
#include <iomanip>
#include <vector>
#include <string>

using namespace std;

int n;
int d[50];
int fib(int i) {
	if (d[i] > 0) return d[i];

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

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


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++: #include<bits/stdc++.h>
const long long INF = INT_MAX / 2;
const long long MOD = 1000000007;
const long double PI = 3.1415926;
#define FOR(i,r,n) for(ll i = (ll)(r); i < (ll)(n); i++)
#define RFOR(i,r,n) for(ll i=(ll)(n-1);i>=r;i--)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define RALL(x) x.rbegin(),x.rend()
#define ll long long int
using namespace std;
ll ans = 0, sum = 0, n, k, cnt = 0, w, h;
string s;
vector<ll> v;
vector < pair<ll, ll > > vp;
vector<vector<ll> > vv(50, vector<ll>(50, INF));
vector<string> vs;
vector<char> vc;
set<ll> st;
map<char, ll> mp;

/*--------------------template--------------------*/

int main()
{
	cin >> n;
	ll a[100];
	fill(a,a+2, 1);
	FOR(i,2,n+1)
	{
		a[i] = a[i - 1] + a[i - 2];
	}
	cout << a[n] << endl;
}

C++: #include <iostream>

using namespace std;

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

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

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,k,n) for(int i = (k); i < (n); i++)
#define REP(i,n) FOR(i,0,n)
#define INF 114514810
#define MOD 1000000007
#define ALL(a) begin(a),end(a)
#define MS(m,v) memset(m,v,sizeof(m))
#define D10  fixed<<setprecision(10)
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int, int> P;
typedef long long ll;
struct edge
{
	int from, to, cost;
	bool operator < (const edge& e) const { return cost < e.cost; }
	bool operator >(const edge& e) const { return cost > e.cost; }
};
///*************************************************************************************///
///*************************************************************************************///
///*************************************************************************************///

int main()
{
	int n; cin >> n;
	int fib[50];
	fib[0] = 1; fib[1] = 1;
	FOR(i, 2, n + 1)
	{
		fib[i] = fib[i - 1] + fib[i-2];
	}
	cout << fib[n] << endl;
	return 0;
}

C++: #include <stdio.h>
#include <stdlib.h>
int main(){
    int n;
    scanf("%d", &n);
    int f[n+2];
    f[0] = 1;
    f[1] = 1;
    for(int i = 2; i <= n; i++) f[i] = f[i-1] + f[i-2];
    printf("%d\n", f[n]);
    return 0;
}

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

long long Fib(int n){
	vector<long long> F(n+1);
	int i;
	F[0]=1;
	F[1]=1;
	for (i=2;i<=n+1;i++){
		F[i]=F[i-1]+F[i-2];
	}
	return F[n];
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	int n;
	cin >> n;
	
	cout << Fib(n);
	return 0;
}

C++: #include <iostream>

using namespace std;

int A[128];
int fib(int n){
  A[0] =1;
  for(int i=1;i<n;++i){
    A[i] =A[i-1];
    if(i>2)A[i]+=A[i-2];
    if(i>3)A[i]+=A[i-3];
  }
  return A[n-1];

}

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

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
//#define ll long long
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 (a>b) { a=b; return 1; } return 0; }
#define rep(i, n) REP(i, 0, n)
#define rep_rev(i, n) for (int (i) = (int)(n) - 1 ; (i) >= 0 ; --(i))
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for(int i = x; i < n; i++)
#define all(x) (x).begin(),(x).end()
ll tmp1,tmp2,tmp3;
const ll mod = 1000000007;
const int INF = 1e9;
const ll INFLONG = 1e18;
void swap(ll *x,ll *y){
  ll tmp;
  tmp = *x;
  *x = *y;
  *y = tmp;
}
vector<ll> fib(100,-1);
ll calc_fib(ll k){
  if(fib[k] != -1){
    return fib[k];
  }
  fib[k] = calc_fib(k-1) + calc_fib(k-2);
  return fib[k];
}
int main(){
  fib[0] = 1;
  fib[1] = 1;
  ll n;
  cin >> n;
  rep(i,n){
    calc_fib(i);
  }
  cout << calc_fib(n) << endl;
}

C++: #include<math.h>
#include<cmath>
#include<bitset>
#include<stdio.h>
#include<string>
#include<map>
#include<algorithm>
#include<vector>
#include<iostream>
#include<utility>
using namespace std;
int main(){
  long long int i,n,dp[50];
  scanf("%lld\n",&n);
  dp[0]=1,dp[1]=1;
  for(i=2;i<=n;i++){
    dp[i]=dp[i-1]+dp[i-2];
  }
  printf("%lld\n",dp[n]);
  return 0;
}

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

#define MAX 45

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

int main()
{
    int C;

    cin >> C;

    //cout << fibonacci(C) << endl;

    int F[MAX];

    F[0] = 1;
    F[1] = 1;

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

    cout << F[C] << endl;

    return 0;
}