// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define double ld
#define rep(i,n) for (int i = 0; i < (int)(n); i++)
#define rep1(i,n) for (int i = 1; i <= (int)(n); i++)
#define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i,n) for (int i = (int)(n); i >= 1; i--)
#define loop(i,a,B) for (int i = a; i B; i++)
#define loopR(i,a,B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define rng(x,l,r) begin(x) + (l), begin(x) + (r)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fst first
#define snd second
template <class Int> auto constexpr inf = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf<int32_t>;
auto constexpr INF64 = inf<int64_t>;
auto constexpr INF   = inf<int>;
#ifdef LOCAL
#include "debug.hpp"
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> {
    vector<T> &data() { return this->c; }
    void clear() { this->c.clear(); }
};
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T,S> const& p) { return os << "(" << p.first << ", " << p.second << ")"; }
template <class T, class S> istream& operator>>(istream& is, pair<T,S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T,d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T,d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T,0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T,d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T,d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
const int dx[] = { 1,0,-1,0,1,-1,-1,1 };
const int dy[] = { 0,1,0,-1,1,1,-1,-1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
// [a,b]
template <class Int> Int rand(Int a, Int b) { static mt19937_64 mt{random_device{}()}; return uniform_int_distribution<Int>(a,b)(mt); }
i64 irand(i64 a, i64 b) { return rand<i64>(a,b); }
u64 urand(u64 a, u64 b) { return rand<u64>(a,b); }
// <<<
// >>> lazy segment tree

template <class Handler>
struct LazySegtree : Handler {
    static int32_t btmbit(int64_t x) { return x ? __builtin_ctzll(x) : -1; }
//    static int32_t btmbit(int32_t x) { return x ? __builtin_ctz(x) : -1; }

    using Value = typename Handler::Value;
    using Lazy = typename Handler::Lazy;
    using Handler::unit_value; // () -> Value
    using Handler::unit_action; // () -> Lazy
    using Handler::merge; // (Value,Value) -> Value
    using Handler::act; // (Lazy,Lazy&,Value&) -> void

    vector<Value> v;
    vector<Lazy> lz;
    int n;
    mutable Lazy tmp;

    LazySegtree() {}
    template <class... T> LazySegtree(T&&... x) { init(forward<T>(x)...); }

    template <class F, class = decltype(declval<F>()(0))>
    void init(int n, F gen)  {
        assert(n >= 0); this->n = n;
        v.resize(2*n); lz.assign(n, unit_action());
        for (int i = 0; i < n; i++) v[n+i] = gen(i);
        for (int i = n-1; i >= 1; i--) v[i] = merge(v[2*i],v[2*i+1]);
    }
    void init(int n) { init(n, [&](int) { return unit_value(); }); }
    void init(int n, Value const& x) { init(n, [&](int) { return x; }); }
    void init(vector<Value> const& v) { init(v.size(), [&](int i) { return v[i]; }); }
    int size() const { return n; }


    void act(Lazy const& x, int i) { act(x, (i < n ? lz[i] : tmp), v[i]); }
    void flush(int k) {
        if (n <= k || lz[k] == unit_action()) return;
        act(lz[k], 2*k);
        act(lz[k], 2*k+1);
        lz[k] = unit_action();
    }
    void flush(int l, int r) {
        for (int p = __lg(l += n), q = __lg(r += n-1); q; --p,--q) {
            flush(l >> p); flush(r >> q);
        }
    }
    void build(int i) {
        i += n; i >>= btmbit(i);
        while (i >>= 1) v[i] = merge(v[2*i],v[2*i+1]);
    }
    Value get(int l, int r) {
        assert(0 <= l); assert(l <= r); assert(r <= n);
        flush(l,r);
        Value x = unit_value(), y = unit_value();
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l&1) x = merge(x,v[l++]);
            if (r&1) y = merge(v[--r],y);
        }
        return merge(x,y);
    }
    void apply(int l, int r, Lazy const& x) {
        assert(0 <= l); assert(l <= r); assert(r <= n);
        flush(l,r);
        for (int a = l+n, b = r+n; a < b; a >>= 1, b >>= 1) {
            if (a&1) act(x, a++);
            if (b&1) act(x, --b);
        }
        build(l); build(r);
    }
    Value operator[](int i) const { return get(i); }
    Value get(int i) const {
        assert(0 <= i); assert(i < n);
        Value x = v[i += n];
        while (i >>= 1) act(lz[i], tmp, x);
        return x;
    }
    void set(int i, Value const& x) {
        assert(0 <= i); assert(i < n);
        for (int p = __lg(i += n); p; --p) flush(i >> p);
        for (v[i] = x; i >>= 1; ) v[i] = merge(v[2*i],v[2*i+1]);
    }
    vector<Value> dat() const {
        vector<Value> ret(size());
        for (int i = 0; i < size(); i++) ret[i] = get(i);
        return ret;
    }
};

// <<<

struct RangeMinAdd {
    using Value = int;
    using Lazy = int;
    constexpr static Value unit_value() { return INF; }
    constexpr static Lazy unit_action() { return 0; }
    constexpr static Value merge(Value x, Value y) {
        return min(x,y);
    }
    static void act(Lazy x, Lazy &y, Value &z) {
        y += x, z += x;
    }
};

int32_t main() {
    int n; cin >> n;
    vector<int> c(n), d(n);
    rep (i,n) cin >> c[i] >> d[i];
    d.eb(0);

    vector<tuple<int, int, int>> st;
    vector<int> dp(n+1, INF);
    LazySegtree<RangeMinAdd> seg(n+1);
    dp[0] = 0;
    rep (i,n) {
        seg.set(i, dp[i] + c[i] - d[i]);
        while (st.size()) {
            auto [val, l, r] = st.back();
            if (val >= c[i]) {
                st.pop_back();
                seg.apply(l, r, -(val-c[i]));
            } else {
                break;
            }
        }
        int l = (st.size() ? get<2>(st.back()) : 0);
        int r = i+1;
        if (l < r) st.eb(c[i], l, r);

        dp[i+1] = seg.get(0, i+1);
    }

    cout << sumof(all(c)) + sumof(all(d)) + dp[n] << endl;

}