#include <bits/stdc++.h> 

using i64 = long long; 
using u64 = unsigned long long; 
using u32 = unsigned; 

using u128 = unsigned __int128; 
using i128 = __int128; 

struct DSU {
    std::vector<int> f, siz;
    
    DSU() {}
    DSU(int n) {
        init(n);
    }
    
    void init(int n) {
        f.resize(n);
        std::iota(f.begin(), f.end(), 0);
        siz.assign(n, 1);
    }
    
    int find(int x) {
        while (x != f[x]) {
            x = f[x] = f[f[x]];
        }
        return x;
    }
    
    bool same(int x, int y) {
        return find(x) == find(y);
    }
    
    bool merge(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) {
            return false;
        }
        siz[x] += siz[y];
        f[y] = x;
        return true;
    }
    
    int size(int x) {
        return siz[find(x)];
    }
};

struct Edge {
	i64 w;
	int u, v;
	bool operator<(const Edge& o) const { return w < o.w; }
};

i64 kruskal(int n, std::vector<Edge> edges) {
	std::sort(edges.begin(), edges.end());
	DSU dsu(n);
	i64 total = 0;
	int taken = 0;
	for(const Edge& e : edges) {
		if(dsu.merge(e.u, e.v)) {
			total += e.w;
			taken ++;
		}
	}
	return taken == n - 1 ? total : -1;
}
void solve() {
	int N; std::cin >> N;
	std::vector<i64> C(N), D(N);

	i64 Z = 0;
	for(int i = 0; i < N; i ++) {
		std::cin >> C[i] >> D[i];
		Z += C[i];
	}

	std::vector<Edge> edges;
	for(int i = 0; i < N; i ++) edges.push_back({C[i], 0, i + 1});
	for(int i = 1; i < N; i ++) edges.push_back({D[i], i, i + 1});

	std::cout << Z + kruskal(N + 1, edges) << "\n";
} 

int main() { 
	std::ios::sync_with_stdio(false); 
	std::cin.tie(nullptr); 

	int T = 1; 
	//std::cin >> T; 

	while (T--) { 
		solve(); 
	} 
	return 0; 
}