#include <bits/stdc++.h>

using namespace std;

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

int main() {
	float a[8] = {1, 3, 4, -9, 6, 7, -5, 4};
	cout << sum(a, 0, 7);
	return 0;
}