#include <iostream>
using namespace std;

int main() {
    int N;
    while (cin >> N) {  
        if (N == 1) {
            cout << 1 << endl;
        } else if (N == 2) {
            cout << 2 << endl;
        } else {
            unsigned long long a = 1, b = 2, c;
            for (int i = 3; i <= N; ++i) {
                c = a + b;
                a = b;     
       &nbs...