#include <bits/stdc++.h>

using namespace std;
static const long long INF = 1e18;

int main() {
    size_t N;
    cin >> N;
    vector<long long> C(N), D(N);
    for (int i = 0; i < N; i++) cin >> C[i] >> D[i];

    auto get_min = [&](int l, int r) {
        return *min_element(C.begin() + l, C.begin() + r);
    };

    deque<pair<long long, long long> > Q;
    auto add_back = [&](long long a, long long b) {
        long long v = a;
        while (Q.size() && Q.back().second <= b) {
            v = max(Q.back().first, v);
            Q.pop_back();
        }

        if(Q.empty() || Q.back().first <= v ) {
            Q.emplace_back(v, b);
        }
    };

    auto query = [&](){
        return Q.front().first + Q.front().second;
    };

    add_back(D[0], -C[0]);
    for (int i = 1; i < N; i++) {
        add_back(query() + D[i], -C[i]);
    }
    cout << accumulate(C.begin(), C.end(), 0ll) + accumulate(D.begin(), D.end(), 0ll) - query() << endl;


}