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

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

bool comp(pii a, pii b){
    return min(-a.first,-a.first+a.second-b.first) > min(-b.first,-b.first+b.second-a.first);
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    vector<pii>a(n+1);
    for(int i = 1; i<=n; i++){
        cin >> a[i].first >> a[i].second;
    }
    sort(a.begin()+1,a.end(),comp);
    int cur = 0;
    int mn = 0;
    for(int i = 1; i<=n; i++){
        //cout << a[i].first << '\n';
        cur -= a[i].first;
        mn = min(mn,cur);
        cur += a[i].second;
    }
    cout << abs(mn) << '\n';
    return 0;
}