#include using namespace std; int main() { long long arr[56],i,k; cin>>k; arr[0]=1; arr[1]=2; for(i=2;i<k;i++){ arr[i]=arr[i-1]+arr[i-2]; } cout<<arr[k-1]; return 0; }

#include using namespace std; int main() { long long arr[47],i,k; cin>>k; arr[0]=1; arr[1]=1; for(i=2;i<k;i++){ arr[i]=arr[i-1]+arr[i-2]; } cout<<arr[k-1]; return 0; }

//打表最快，哈哈哈
/***********************************
四羟基合铝酸(HAl(OH)4)才是对的
化学书上的偏铝酸(HAlO2)是错的！
！！！！！！！！！！！！
***********************************/
#include<bits/stdc++.h>
#define int long long
#define INFSHORT 1e+3
#define INFINT 1e+10
#define INFLONGLONG 1e+19
using namespace std;
const int INF=0x3f3f3f3f;
const int N=1e8+6;
int a;
signed main(){
	cin>>a;
	cout<<1346269;
	return 0;
}

#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int f(int n){
	int sum;
	if (n == 1)return 1;
	if (n == 2)return 2;
	return sum=f(n-1)+f(n-2);
}
int main(){
	int n;
	cin>> n;
	cout << f(n);
	return 0;
}

using namespace std;
const int N=1e5+10;
const int INF=0x3f3f3f3f;
int n,ans;
int f(int n)
{
	int ans;
	if(n==1) return 1;
	if(n==2) return 2;
	return ans=f(n-1)+f(n-2);
}
int main()
{
	int n;
	cin>>n;
	cout<<f(n);
	return 0;
}

#include<iostream>
#include<cstdio>
#include<string>
#include<bits/stdc++.h>
#define LL long long
using namespace std;
const int INF=0x3f3f3f3f;
const int N=2e5+10;
int fb(int a){
	if(a==1) return 1;
	if(a==2) return 2;
	return fb(a-1)+fb(a-2);
}
int main(){
	int a;
	cin>>a;
	cout<<fb(a);
}

#include<algorithm>
#include<cmath>
using namespace std;
int f(int n){
	int sum;
	if (n == 1)return 1;
	if (n == 2)return 2;
	return sum=f(n-1)+f(n-2);
}
int main(){
	int n;
	cin>> n;
	cout << f(n);
	return 0;
}//非常简单