L.cc

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
using namespace std;
typedef long long ll;
#define prt(k) cout << #k " = " << k << endl;

const int N = 50020;

struct data
{
    int w, s;
};
data a[N];
bool cmp(data a1, data a2)
{
    int w1 = a1.w, s1 = a1.s;
    int w2 = a2.w, s2 = a2.s;
    return max(-s1, w1-s2) < max(-s2, w2-s1);
}
int n;
int main()
{
    while(cin >> n, n)
    {
        for(int  i = 0; i < n; i ++) scanf("%d%d", &a[i].w, &a[i].s);
        sort(a, a+n, cmp);
        ll ans = -1e9, tot = 0;
        for(int  i = 0; i < n; i++)
        {
            ans = max(ans, tot - a[i].s);
            tot += a[i].w;
        }
        cout << ans << endl;
    }
}