#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long mod = 1000000007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;

class UnionFind {
public:
	vector<ll> Parent;
	UnionFind(ll N) {
		Parent = vector<ll>(N, -1);
	}
	ll root(ll A) {
		if (Parent[A] < 0) {
			return A;
		}
		return Parent[A] = root(Parent[A]);
	}

	ll size(ll A) {
		return -Parent[root(A)];
	}

	bool connect(ll A, ll B) {
		A = root(A);
		B = root(B);
		if (A == B) {
			return false;
		}
		if (size(A) < size(B)) {
			swap(A, B);
		}

		Parent[A] += Parent[B];
		Parent[B] = A;

		return true;
	}

};

class Edge {
public:
	ll source, target, cost;
	Edge(ll source = 0, ll target = 0, ll cost = 0) :
		source(source), target(target), cost(cost) {}
	bool operator<(const Edge& e)const {
		return cost < e.cost;
	}
};

ll kuraskal(ll N, vector<Edge>& edges) {
	ll totalCost = 0;
	sort(edges.begin(), edges.end());
	UnionFind uni(N + 1);
	ll source, target;
	for (ll i = 0; i < edges.size(); i++) {
		Edge e = edges[i];
		if (uni.root(e.source) != uni.root(e.target)) {
			totalCost += e.cost;
			uni.connect(e.source, e.target);
		}
	}
	return totalCost;
}

int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/
	ll N; scanf("%lld", &N);
	vector<ll> c(N), d(N); for (ll i = 0; i < N; i++) scanf("%lld %lld", &c[i], &d[i]);
	vector<Edge> edges;
	for (ll i = 0; i < N - 1; i++) {
		edges.emplace_back(i, i + 1, d[i + 1]);
	}
	ll sum = 0;
	for (ll i = 0; i < N; i++) {
		sum += c[i];
		edges.emplace_back(i, N, c[i]);
	}
	cout << kuraskal(N + 1, edges) + sum << endl;
	return 0;
}