#include <bits/stdc++.h>

using namespace std;

float tongDuong(float a[], int l, int r) {
	if (r == l) {
		if (a[l] > 0) return a[l];
		else return 0;
	} else {
		int m = (l + r) / 2;
		return tongDuong(a, l, m) + tongDuong(a, m + 1, r);
	}
}

int main() {
	float a[] = {1.2, 3.4, 4.5, 9.1, 6.3, 7.2, 5.4, 4.6, 4.9, 8.5, 9.9, 0.5, 6, 8, 10.6, -3, 3, 4, -2, -5};
	cout << "Tong duong: " << tongDuong(a, 0, 19) << endl;
	return 0;
}