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

typedef long long LL;
typedef pair<int, int> PII;
#define fi first
#define se second
const int N=5e5+5;
int n;
PII Cow[N];

int main(){
    cin>>n;
    int w, s;
    for(int i=0; i<n; ++i){
        cin>>w>>s;
        Cow[i]={w, s};
    }
    sort(Cow, Cow+n, [&](PII c1, PII c2){
        return c1.fi+c1.se<c2.fi+c2.se;
    });
    int res=-1e9-5;
    int sum=0;
    for(int i=0; i<n; ++i){
        res=max(res, sum-Cow[i].se);
        sum+=Cow[i].fi;
    }
    cout<<res<<endl;

    return 0;
}