// Problem: D. 摆烂
// Contest: undefined - NOIP2024训练赛 08
// URL: http://www.noi.ac/contest/1160/problem/2767
// Memory Limit: 1024 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
//#define int long long
#define fi first
#define se second
#define PII pair<int, int>

using namespace std;

const int N = 2e6 + 10, M = 1e6 + 10, mod = 1e9 + 7, INF = 0x3f3f3f3f;

int n, m, q, ans;
int dp[N];
PII s[N];

vector<int> v;

struct Tree
{
	int l, r;
	int mn[3];
}tr[N << 2];

inline void pushdown(int x, int op) 
{
	tr[2 * x].mn[op] = min(tr[2 * x].mn[op], tr[x].mn[op]);
	tr[2 * x + 1].mn[op] = min(tr[2 * x + 1].mn[op], tr[x].mn[op]);
	// tr[x].mn[op] = min(tr[2 * x].mn[op], tr[2 * x + 1].mn[op]);
}

void build(int x, int l, int r)
{
	tr[x].l = l, tr[x].r = r, tr[x].mn[0] = tr[x].mn[1] = INF;
	if(l == r) return;
	int mid = l + r >> 1;
	build(2 * x, l, mid);
	build(2 * x + 1, mid + 1, r);
}

void change(int x, int l, int r, int v, int op)
{
	if(l > r) return;
	if(tr[x].l >= l && tr[x].r <= r) 
	{
		tr[x].mn[op] = min(tr[x].mn[op], v);
		return;
	}
	pushdown(x, op);
	int mid = tr[x].l + tr[x].r >> 1;
	if(l <= mid) change(2 * x, l, r, v, op);
	if(r > mid) change(2 * x + 1, l, r, v, op);
}

int query(int x, int p, int op)
{
	if(tr[x].l == tr[x].r) return tr[x].mn[op];
	pushdown(x, op);
	int mid = tr[x].l + tr[x].r >> 1;
	if(p <= mid) return query(2 * x, p, op);
	else return query(2 * x + 1, p, op);
}

signed main()
{
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n;
  	for(int i = 1; i <= n; i ++) 
  	{
    	cin >> s[i].fi >> s[i].se;
    	while(v.size() && s[v.back()].se <= s[i].se) v.pop_back();
    	v.push_back(i);
  	}
  	for (int i = 1; i <= v.size(); i ++) s[i] = s[v[i - 1]];
  	
  	n = v.size();
 	// for(int i = 1; i <= n; i ++) cout << s[i].fi << ' ' << s[i].se << '\n';
 	build(1, 1, n);
  	for(int i = 0; i <= n; i ++)
    {
    	if(i) dp[i] = min(query(1, i, 0), query(1, i, 1) + s[i].fi);
    	// cout << dp[i] << ' ';
    	int id = lower_bound(s + 1, s + n + 1, make_pair(dp[i], 0)) - s;
    	change(1, i + 1, id - 1, dp[i] + 2 * s[i + 1].se, 0);
    	change(1, id, n, 2 * s[i + 1].se, 1);
    	// for(int j = 1; j <= n; j ++) cout << query(1, j, 0) << ' ';
    	// cout << '\n';
    	// for(int j = 1; j <= n; j ++) cout << query(1, j, 1) << ' ';
    	// cout << '\n';
    }
  	cout << dp[n] << '\n';
	return 0;
}