//
//  na 2767.cpp
//  Competitive Programming
//
//  Created by m2 on 2024/11/18.
//

#include <stdio.h>
#include <iostream>
#include <set>
#include <algorithm>
using namespace std;
typedef long long int ll;
#ifdef MAC_OS_VERSION_11_0
const int maxn = 1e4 + 5, maxdep = 21;
#else
const int maxn = 2e6 + 5, maxdep = 21; // max 2^20
#endif
int n, st[maxn][maxdep], lg2[maxn], a[maxn], t[maxn];
inline void qread(int &var){
    var = 0;
    char reg = getchar();
    while(reg - 48 >= 10u)
        reg = getchar();
    do{
        var = (var << 1) + (var << 3) + (reg ^ 48);
        reg = getchar();
    }while(reg - 48 < 10u);
}
struct Node{
    int t, a;
    inline void read(){ qread(t); qread(a); }
    inline bool operator < (const Node &other) const{
        return t < other.t;
    }
}ns[maxn];
ll dp[maxn];
int que[maxn], qs = 0, qe = 0;
inline void init_st(){
    for(int i = n; i; --i){
        st[i][0] = a[i];
        for(int j = 1; j < maxdep; ++j)
            st[i][j] = max(st[i][j - 1], st[min(n, i + (1 << j))][j - 1]);
    }
    lg2[1] = 0;
    for(int i = 2; i <= n; ++i)
        lg2[i] = lg2[i >> 1] + 1;
}
inline int query(int lt, int rt){
    int dep = lg2[rt - lt + 1];
    return max(st[lt][dep], st[rt - (1 << dep) + 1][dep]);
}
multiset<ll> vs;
int main(){
    cin.tie(0)->sync_with_stdio(false);
    qread(n);
    for(int i = 1; i <= n; ++i)
        ns[i].read();
    sort(ns + 1, ns + n + 1);
    for(int i = 1; i <= n; ++i){
        t[i] = ns[i].t;
        a[i] = ns[i].a;
    }
#ifndef MAC_OS_VERSION_11_0
    if(n <= 1000){
        for(int i = 1; i <= n; ++i){
            int ma = a[i];
            dp[i] = 0x1f1f1f1f1f1f1f1f;
            for(int j = i - 1; j >= 0; --j){
                dp[i] = min(dp[i], max(dp[j], ll(t[i])) + 2 * ma);
                ma = max(ma, a[j]);
            }
        }
        cout << dp[n] << endl;
        return 0;
    }
#endif
    init_st();
    int ptr = 0;
    vs.insert(0);
    for(int i = 1; i <= n; ++i){
//        cerr << "#" << i << endl;
        while(ptr + 1 < i && dp[ptr + 1] <= t[i])
            ++ptr;
//        cerr << "ptr = " << ptr << endl;
        dp[i] = t[i] + 2 * query(ptr + 1, i);
        while(qs <= qe && dp[que[qs]] <= t[i]){
            vs.erase(vs.find(dp[que[qs]] + 2 * a[que[qs]]));
            ++qs;
        }
        while(qs <= qe && ns[que[qe]].a < a[i]){
            vs.erase(vs.find(dp[que[qe]] + 2 * a[que[qe]]));
            --qe;
        }
//        cerr << "current que: ";
//        for(int i = qs; i <= qe; ++i)
//            cerr << que[i] << ' ';
//        cerr << endl;
        if(qs <= qe)
            dp[i] = min(dp[i], *vs.begin());
        if(qs > qe || (a[que[qe]] > a[i])){
            que[++qe] = i;
            vs.insert(dp[i] + 2 * a[i]);
        }
//        cerr << "dp #" << i << " = " << dp[i] << endl;
    }
    cout << dp[n] << endl;
    return 0;
}