#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (ll i=(ll)from; i<(ll)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }

struct item { ll C, D; };

// ----------------------------------------------------------------------
// ----------------------------------------------------------------------

struct UnionFind {
  vector<int> par, s; 
  UnionFind(int N) : par(N), s(N) { rep(i,N) { par[i] = i; s[i] = 1; } }
  int root(int x) { return par[x]==x ? x : par[x] = root(par[x]); }
  int size(int x) { return par[x]==x ? s[x] : s[x] = size(root(x)); }
  void unite(int x, int y) { int rx=root(x), ry=root(y); if (rx!=ry) { s[rx] += s[ry]; par[ry] = rx; } }
  bool same(int x, int y) {  int rx=root(x), ry=root(y); return rx==ry; }
};

struct edge { ll from; ll to; ll d; };
vector<edge> e;

ll Kruskal(int N) {
  UnionFind tree(N);
  sort(all(e), [](const edge &x, const edge &y){return x.d<y.d;});
  ll result = 0;
  for (auto x: e) {
    if (tree.same(x.from, x.to)) continue;
    result += x.d;
    tree.unite(x.from,x.to);
  }
  return result;
}

// ----------------------------------------------------------------------
// ----------------------------------------------------------------------

int main() {
  int N; cin >> N;
  item it[N]; rep(i,N) cin >> it[i].C >> it[i].D;

  rep(i,N) {
    e.push_back({0,i+1,it[i].C});
    if (i!=0) e.push_back({i,i+1,it[i].D});
  }
  ll result = 0; rep(i,N) result += it[i].C;
  result += Kruskal(N+1);
  cout << result << endl;
  return 0;
}