#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>

using namespace std;

typedef long long LL;

const int N = 100010;
const LL INF = 9e18;

LL f[N][N], ans, ret;
int n, c[N], d[N];

int main() {
    // freopen("shopping.in", "r", stdin);
    // freopen("shopping.out", "w", stdout);

    scanf("%d", &n);
    for (int i = 1; i <= n; ++i) {
        scanf("%d%d", &c[i], &d[i]);
        ans += c[i];
    }

    memset(f, 0x3f, sizeof(f));
    f[1][1] = c[1];
    for (int i = 2; i <= n; ++i) {
        for (int j = 1; j < i; ++j) {
            f[i][i] = min(f[i][i], f[i - 1][j] + c[i]);
            if (c[j] <= c[i]) {
                f[i][j] = min(f[i][j], f[i - 1][j] + d[i]);
            } else {
                f[i][i] = min(f[i][i], f[i - 1][j] + d[i] + c[i] - c[j]);
            }
        }
    }

    ret = INF;
    for (int i = 1; i <= n; ++i) ret = min(ret, f[n][i]);

    printf("%lld\n", ans + ret);

    return 0;
}