include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
const int N = 50;
int q[N];
int n;
int main(){
cin >> n;
q[1] = 1 ;
q[2] = 2;
if(n==1 || n==2){
cout << n << endl;
return 0;
}
for(int i = 3;i <= n;i ++){
q[i] = q[i - 1] + q[i - 2];
}
cout << q[n];
return 0;
}