#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++)
    #define gc() getchar()
    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 Segment_Tree{
    int Mn[N << 2];
    Segment_Tree(){memset(Mn, 0x3f, sizeof(Mn));}
    int qry(int u, int l, int r, int L, int R){
        if(L > R) return Mn[0];
        if(L <= l && r <= R) return Mn[u];
        int mid = (l + r) >> 1;
        if(R <= mid) return qry(u << 1, l, mid, L, R);
        if(L > mid) return qry(u << 1 | 1, mid + 1, r, L, R);
        return min(qry(u << 1, l, mid, L, R), qry(u << 1 | 1, mid + 1, r, L, R));
    }
    void upd(int u, int l, int r, int p, int k){
        if(l == r){
            Mn[u] = min(Mn[u], k);
            return ;
        }
        int mid = (l + r) >> 1;
        if(p <= mid) upd(u << 1, l, mid, p, k);
        else upd(u << 1 | 1, mid + 1, r, p, k);
        Mn[u] = min(Mn[u << 1], Mn[u << 1 | 1]);
    }
}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(1, 0, n, 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] = min(T.qry(1, 0, n, pos + 1, i - 1), val[i].first + 2ll * val[pos + 1].second);
        if(i == n){
            write(f[n]);
            break;
        }
        T.upd(1, 0, n, i, f[i] + 2 * val[i + 1].second);
    }
}