#include<bits/stdc++.h>
using namespace std;
long long a[47];//开数组存
int main(){
	int k;
	cin >> k;
	a[1] = 1;
	a[2] = 1;
    //设置前两项(注意位置)
	for (int i = 3;i < 47;i++){
		a[i] = a[i - 1] + a[i - 2];//按照菲波那契数列的思路拓展
	}
	cout << a[k];//输出第k个
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
	int k,a,b,c;
	cin>>k;
	a=1;
	b=1;
	if(k<=2)
	  c=1;
	else
	{
	 for(int i=3;i<=k;i++)
	 {
	  c=a+b;
	  a=b;
	  b=c;
	 }cout<<c;
	}  
	return 0;
}

using namespace std;
int main()
{
 	long long a = 1, b = 1,c = 0 ,n;
	int d;
	cin >> n; 	
	for(int i = 1;i <= n;i++)
	{
        cin >> d;
        for(int j = 2;j <= d;j++)
		{
			c = a;
			a = b;
			b = b + c;		       
		}
		cout << a << endl;	        	 		 
		a = 1;
		b = 1;
	}
}
`

#include<bits/stdc++.h>
using namespace std;
int main(){
int n,a,b,c;
cin>>n;
a=1;
b=1;
if(n<=2){
c=1;
}
else{
for(int i=3;i<=n;i++){
c=a+b;
a=b;
b=c;
}
cout<<c;
}
return 0;
}