#include <bits/stdc++.h>

using namespace std;

const int BUFFER_SIZE = 1 << 20;
char rb[BUFFER_SIZE], *rp = rb, *rt = rb;
inline char read_char() {
    return rp == rt ? (rt = rb + fread(rb, 1, BUFFER_SIZE, stdin), rp = rb, *rp ++) : *rp ++;
}
inline int read_int() {
    int x = 0;
    char ch = read_char(), flag = 0;
    while (ch != '-' && (ch < '0' || ch > '9')) {
        ch = read_char();
    }
    if (ch == '-') {
        flag = 1;
        ch = read_char();
    }
    for (x = 0; ch >= '0' && ch <= '9'; ch = read_char()) {
        x = x * 10 + (ch - '0');
    }
    return flag ? -x : x;
}

const int MAX_N = 2000000 + 5;
typedef long long i64;
const i64 INF64 = 1e18;

int N;
int b[MAX_N], a[MAX_N], q[MAX_N], qh, qt;
i64 f[MAX_N], g[MAX_N][22];

int main() {
    N = read_int();
    for (int i = 1; i <= N; i ++) {
        b[i] = read_int();
        a[i] = read_int();
    }
    q[qh = 0] = 0, qt = 1, a[0] = 1e9 + 1;
    for (int i = 1; i <= N; i ++) {
        f[i] = INF64;
        for (; qh < qt && a[q[qt - 1]] < a[i]; qt --);
        q[qt ++] = i;
        for (; qh < qt && f[q[qh]] < b[i]; ) qh ++;
        f[i] = b[i] + 2ll * a[q[qh]];
        if (qh + 1 < qt) {
            int p = qt - 1, j;
            g[p][0] = f[q[p - 1]] + 2ll * a[q[p]];
            for (j = 1; p - (1 << j) + 1 > qh; j ++) {
                g[p][j] = min(g[p][j - 1], g[p - (1 << j - 1)][j - 1]);
            }
            j --;
            i64 tf = min(g[p][j], g[qh + (1 << j)][j]);
            f[i] = min(f[i], tf);
        }
    }
    printf("%lld\n", f[N]);
    return 0;
}