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

int main() {
	int n; cin >> n;
	int64_t a[2 * n];
	int64_t sum = 0;
	for(int i = 0; i < 2 * n; ++i) {
		cin >> a[i];
		sum += a[i];
	}
	int64_t l[n + 1] = {}, r[n + 1] = {};
	for(int i = 1; i <= n; ++i) {
		l[i] = l[i - 1] + a[(i - 1) * 2];
		r[i] = r[i - 1] + a[(2 * n - 2 * (i - 1)) - 1];
	}
	int64_t ans = -1e18;
	for(int i = 0; i <= n; ++i) {
		ans = max(ans, (l[i] + r[n - i]) - (sum - (l[i] + r[n - i])));
	}
	cout << ans << '\n';
	return 0;
}