#include <bits/stdc++.h>
#define int long long 
using namespace std;
const int N = 2e6 + 100;
namespace IO{
    const int SI = (1 << 21) + 5;
    char IB[SI], *IS = IB, *IT = IB;
    #define gc() (IS == IT ? ((IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT) ? EOF : *IS++) : *IS++)
    inline int read(){
        int x = 0, fg = 1;
        char ch = gc();
        while(ch < '0' || ch > '9'){if (ch == '-') fg = -1;ch = gc();}
        while(ch >= '0' && ch <= '9'){x = (x << 1) + (x << 3) + ch - '0';ch = gc();}
        return x * fg;
    }
    inline void write(int x){
        if(x < 0) putchar('-'), x = -x;
        static int sta[70];
        int tp = 0;
        do{sta[tp++] = x % 10, x /= 10;}while(x);
        while(tp) putchar(sta[--tp] + '0');
        putchar('\n');
    }
}
using namespace IO;

int n, cnt;
struct BIT{
    int Mn[N];
    BIT(){memset(Mn, 0x3f, sizeof(Mn));}
    int qry(int x){
        int r = Mn[N - 1];
        while(x){
            r = min(r, Mn[x]);
            x -= (x & -x);
        }
        return r;
    }
    int Qry(int p){return qry(n - p + 1);}
    void upd(int x, int k){
        while(x <= n + 1){
            Mn[x] = min(Mn[x], k);
            x += (x & -x);
        }
    }
    void Upd(int p, int k){upd(n - p + 1, k);}
}T;
pair<int, int> val[N];
int f[N];
int32_t main(){
    n = read();
    for(int i = 1;i <= n;i++){
        int x = read(), y = read();
        while(cnt > 0 && y > val[cnt].second) cnt--;
        val[++cnt] = {x, y};
    }
    n = cnt;
    f[0] = 0;T.Upd(0, f[0] + 2 * val[1].second);
    for(int i = 1;i <= n;i++){
        int t = val[i].first;
        int lft = 1, rit = i - 1, pos = 0;
        while(lft <= rit){
            int mid = (lft + rit) >> 1;
            if(f[mid] <= t) pos = mid, lft = mid + 1;
            else rit = mid - 1;
        }
        f[i] = T.Qry(pos + 1);
        f[i] = min(f[i], val[i].first + 2ll * val[pos + 1].second);
        if(i == n){
            write(f[n]);
            return 0;
        }
        T.upd(i, f[i] + 2 * val[i + 1].second);
    }
}