80 Code:

#include <bits/stdc++.h>
using namespace std;

int main() {
	long long x = 0, k;
	cin >> k;
	long long a[k] = {1, 1};
	for (int i = 2; i < k; i++) {
		a[i] = a[i - 1] + a[i - 2];
	}
	if (k == 0) {
		cout << "0.00";
	} else
		cout << a[k - 1] << ".00";
	return 0;
}