//和国王游戏类似
//国王游戏结论：按照每个大臣左右手数的乘积从小到大排序
//结论：按照每头牛的重量和强壮度的和从小到大排序为最优化
//证明和国王游戏一样
#include <iostream>
#include <algorithm>
#include <cstdio>
#define x first
#define y second
using namespace std;

const int N = 50010;
typedef pair<int , int> PII;
PII cows[N];
int n;
int main (){
    scanf ("%d" , &n);
    for (int i = 0;i < n;i++){
        int w = 0;
        int s = 0;
        scanf ("%d %d" , &w , &s);
        cows[i] = {w + s, w};
    }
    //按照每头牛的重量和强壮度的和从小到大排序
    sort(cows , cows + n);
    int res = -1e9;
    int cnt = 0;
    for (int i = 0;i < n;i++){
        res = max(res , cnt - cows[i].x + cows[i].y);
        cnt += cows[i].y;
    }
    cout << res << endl;
    return 0;
}