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

#define int long long

signed main(){
	int n;
	cin >> n;
	int arui[100010];
	int brui[100010];

	for(int i = 0;i < n;i++){
		cin >> arui[i+1] >> brui[i+1];
		arui[i+1] += arui[i];
		brui[i+1] += brui[i];
	}

	int ans = LLONG_MIN;
	for(int i = 0;i <= n;i++){
		int hom = arui[i] + brui[n]-brui[i];
		int tem = brui[i] + arui[n]-arui[i]; 
		ans = max(ans, hom-tem);
	}

	cout << ans << endl;

	return 0;
}