void solve() throws IOException {
		int n = readInt();
		int size = n * (n + 1) / 2;
		this.graph = new List[size];
		for (int i = 0; i < size; i++) {
			graph[i] = new ArrayList<Integer>();
		}

		for (int i = 0; i < n; i++) {
			for (int j = 0; j <= i; j++) {
				if (i * (i + 1) / 2 + j + i + 1 < size) {
					graph[i * (i + 1) / 2 + j].add(i * (i + 1) / 2 + j + i + 1);
					graph[i * (i + 1) / 2 + j].add(i * (i + 1) / 2 + j + i + 2);
				}
			}

		}
		this.init = readIntArray(size);
		out.println(dfs(0));
	}

	int[] init;

	int dfs(int from) {
		int max = -100000;
		for (int i : graph[from]) {
			max = maxInt(dfs(i), max);
		}
		if (max == -100000) {
			max = 0;
		}
		return max + init[from];
	}