#include<bits/stdc++.h>
#define int long long
using namespace std;
struct node{
    int w,s;
};
node t[50010];
bool cmp(node a, node b){
    return a.w + a.s < b.w + b.s;
}
signed main(){
    int n;
    cin >> n;
    for (int i = 0;i < n;i++){
        int x,y;
        cin >> x >> y;
        t[i].w = x;
        t[i].s = y;
    }
    sort (t,t + n,cmp);
    long long h = 0;
    long long f = -1e9-10;
    long long g = 0;
    for (int i = 0;i < n;i++){
        h = g - t[i].s;
        if (h > f){
            f = h;
        }
        g += t[i].w;
    }
    cout << f;
    return 0;
}