#include <bits/stdc++.h>
#define int long long

using namespace std;

bool cmp(const pair<int, int>& a, const pair<int, int>& b) {
    return (a.first - a.second) < (b.first - b.second);
}

main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    vector<pair<int, int>> s(n);
    int a, b;
    for (int i = 0; i < n; i++) {
        cin >> a >> b;
        s[i] = {a, b};
    }
    sort(s.begin(), s.end(), cmp);
    int right = 0;
    for (int i = 0; i < n; i++) {
        int left = s[i].first - s[i].second;
        if (left > right) {
            right = left;
        }
        right += s[i].second;
    }
    cout << right;
}