#include <iostream>
#include <string>
#include <cstring>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>
#include <fstream>
#include <unordered_set>

using namespace std;

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1ll << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>


ll r[110000], r2[110000];
int main() {
	ll n;
	cin >> n;
	REP(i, n) {
		ll a, b;
		cin >> a >> b;
		r[i + 1] = a - b;
		r2[i + 1] = b - a;
	}
	REP(i, n + 1) {
		r[i + 1] += r[i];
	}
	REPR(i, n) {
		r2[i] += r2[i + 1];
	}
	ll ans = 0;
	REP(i, n + 1) {
		ans = max(ans, r[i] + r2[i + 1]);
	}
	cout << ans << endl;
}