#include <iostream>
#include <algorithm>
#include <vector>

using lint = long long;
constexpr lint INF = 1LL << 50;

void solve() {
    int n;
    std::cin >> n;

    std::vector<lint> fs(n + 2, 0), bs(n + 2, 0);
    for (int i = 1; i <= n; ++i) {
        lint x, y;
        std::cin >> x >> y;
        fs[i] = x - y;
        bs[i] = y - x;
    }

    for (int i = 1; i <= n; ++i) fs[i] += fs[i - 1];
    for (int i = n; i >= 1; --i) bs[i] += bs[i + 1];

    lint ans = -INF;
    for (int f = 0; f <= n; ++f) {
        ans = std::max(ans, fs[f] + bs[f + 1]);
    }
    std::cout << ans << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}