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