import java.util.*;
import java.io.*;

public class Main {
	public static void main (String[] args) throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		ArrayList<Path> paths = new ArrayList<>();
		long total = 0;
		for (int i = 1; i <= n; i++) {
		    String[] line = br.readLine().split(" ", 2);
		    int c = Integer.parseInt(line[0]);
		    int d = Integer.parseInt(line[1]);
		    total += c;
		    paths.add(new Path(c, 0, i));
		    if (i > 1) {
		        paths.add(new Path(d, i - 1, i));
		    }
		}
		Collections.sort(paths);
		UnionFindTree uft = new UnionFindTree(n + 1);
		for (Path p : paths) {
		    if (!uft.same(p)) {
		        uft.unite(p);
		        total += p.value;
		    }
		}
		System.out.println(total);
	}
	
	static class UnionFindTree {
	    int[] parents;
	    
	    public UnionFindTree(int size) {
	        parents = new int[size];
	        for (int i = 0; i < size; i++) {
	            parents[i] = i;
	        }
	    }
	    
	    public int find(int x) {
	        if (x == parents[x]) {
	            return x;
	        } else {
	            return parents[x] = find(parents[x]);
	        }
	    }
	    
	    public boolean same(int x, int y) {
	        return find(x) == find(y);
	    }
	    
	    public boolean same(Path p) {
	        return same(p.left, p.right);
	    }
	    
	    public void unite(int x, int y) {
	        if (!same(x, y)) {
	            parents[find(y)] = find(x);
	        }
	    }
	    
	    public void unite(Path p) {
	        unite(p.left, p.right);
	    }
	}
	
	static class Path implements Comparable<Path> {
	    int value;
	    int left;
	    int right;
	    
	    public Path(int value, int left, int right) {
	        this.value = value;
	        this.left = left;
	        this.right = right;
	    }
	    
	    public int compareTo(Path another) {
	        return value - another.value;
	    }
	}
}

class BinaryIndexedTree {
    int size;
    int[] tree;
    
    public BinaryIndexedTree(int size) {
        this.size = size;
        tree = new int[size];
    }
    
    public void add(int idx, int value) {
        int mask = 1;
        while (idx < size) {
            if ((idx & mask) != 0) {
                tree[idx] += value;
                idx += mask;
            }
            mask <<= 1;
        }
    }
    
    public int getSum(int from, int to) {
        return getSum(to) - getSum(from - 1);
    }
    
    public int getSum(int x) {
        int mask = 1;
        int ans = 0;
        while (x > 0) {
            if ((x & mask) != 0) {
                ans += tree[x];
                x -= mask;
            }
            mask <<= 1;
        }
        return ans;
    }
}