#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())
#define endl "\n"

struct UnionFind {
    UnionFind() {}
    UnionFind(int n) {
        resize(n);
    }
    
    void resize(int n) {
        par.resize(n, -1);
    }
    
    int root(int x) {
        if (par[x] < 0) return x;
        return par[x] = root(par[x]);
    }
    
    bool merge(int x, int y) {
        int rx = root(x);
        int ry = root(y);
        if (rx == ry) return false;
        if (par[rx] > par[ry]) swap(rx, ry);
        par[rx] += par[ry];
        par[ry] = rx;
        return true;
    }
    
    bool is_same(int x, int y) {
        return (root(x) == root(y));
    }
    
    int size(int x) {
        return -par[root(x)];
    }
    
private:
    vector<int> par;
};

template<class T>
struct MinimumSpanningTree {
    MinimumSpanningTree() {}
    MinimumSpanningTree(int n) {
        vertex_count = n;
    }
    
    void resize(int n) {
        vertex_count = n;
    }
    
    void add_edge(int from, int to, T cost) {
        edges.emplace_back((Edge){from, to, cost});
    }
    
    T get_total_cost() {
        sort(edges.begin(), edges.end(), [&](const Edge &a, const Edge &b) {
            return a.cost < b.cost;
        });
        UnionFind uf(vertex_count);
        T ans = 0;
        for (int i = 0, lc = (int)edges.size(); i < lc; i++) {
            if (uf.is_same(edges[i].from, edges[i].to)) continue;
            uf.merge(edges[i].from, edges[i].to);
            ans = ans + edges[i].cost;
        }
        return ans;
    }
    
private:
    struct Edge {
        int from, to;
        T cost;
    };
    
    int vertex_count = 0;
    vector<Edge> edges;
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    ll n;
    cin >> n;
    MinimumSpanningTree<ll> mst(n + 1);
    ll ans = 0;
    rep(i, n) {
        ll c, d;
        cin >> c >> d;
        if (i > 0) mst.add_edge(i, i - 1, d);
        mst.add_edge(i, n, c);
        ans += c;
    }
    ans += mst.get_total_cost();
    cout << ans << endl;
    return 0;
}