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

int main() {
  int N;
  cin >> N;

  vector<int> C(N);
  vector<int> D(N);
  for (int i = 0; i < N; ++i) {
    cin >> C[i] >> D[i];
  }

  vector<tuple<int, int, int>> edges;
  for (int i = 0; i < N; ++i) {
    edges.emplace_back(C[i], N, i);
  }

  for (int i = 1; i < N; ++i) {
    edges.emplace_back(D[i], i - 1, i);
  }

  sort(edges.begin(), edges.end());

  vector<int> fa(N + 1);
  iota(fa.begin(), fa.end(), 0);
  function<int(int)> find = [&](int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); };

  int64_t ans = accumulate(C.begin(), C.end(), 0LL);
  for (auto t : edges) {
    int w, u, v;
    tie(w, u, v) = t;
    int fu = find(u);
    int fv = find(v);
    if (fu != fv) {
      fa[fu] = fv;
      ans += w;
    }
  }

  cout << ans << endl;

  return 0;
}