#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,n) for(ll i = 0;i<((ll)(n));i++)
#define reg(i,a,b) for(ll i = ((ll)(a));i<=((ll)(b));i++)
#define irep(i,n) for(ll i = ((ll)(n)-1);i>=0;i--)
#define ireg(i,a,b) for(ll i = ((ll)(b));i>=((ll)(a));i--)

/*
*/

ll n,c[100010],d[100010],ans=0;
vector<ll> v[100010],cost[100010];

ll prim(ll root, vector<ll> v[], vector<ll> c[]){
	ll ans=0;
	int used[100010]={};
	priority_queue<pair<ll,ll>, vector<pair<ll,ll>>, greater<pair<ll,ll>>> Q;
	Q.push({0,root});
	while(!Q.empty()){
		pair<ll,ll> p = Q.top(); Q.pop();
		if(used[p.second]!=0)continue;
		used[p.second]=1;
		ans+=p.first;
		for(int i=0; i<v[p.second].size(); ++i){
			ll q = v[p.second][i];
			if(used[q]==0)Q.push({c[p.second][i], q});
		}
	}
	return ans;
}

void init(){
	cin>>n;
	reg(i,1,n)cin>>c[i]>>d[i];
	reg(i,1,n)ans+=c[i];	
	reg(i,1,n){
		v[i].push_back(0);
		v[0].push_back(i);
		cost[i].push_back(c[i]);
		cost[0].push_back(c[i]);
	}
	reg(i,2,n){
		v[i].push_back(i-1);
		v[i-1].push_back(i);
		cost[i].push_back(d[i]);
		cost[i-1].push_back(d[i]);
	}
}

int main(void){
	init();
	ans += prim(0,v,cost);
	cout<<ans<<endl;
	return 0;
}