#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <deque>
#include <queue>
#include <array>
#include <set>
#include <map>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <cassert>
#include <utility>
#include <tuple>
#include <functional>
#include <bitset>
#include <cstdint>

using namespace std;
using i64 = int64_t;
using i32 = int32_t;
template<class T, class U> void init_n(vector<T>& v, size_t n, U x) 
{ v = vector<T>(n, x); }
template<class T> void init_n(vector<T>& v, size_t n) { init_n(v, n, T()); }
template<class T> void read_n(vector<T>& v, size_t n, size_t o = 0) 
{ v = vector<T>(n+o); for (size_t i=o; i<n+o; ++i) cin >> v[i]; }
template<class T> void read_n(T a[], size_t n, size_t o = 0)
{ for (size_t i=o; i<n+o; ++i) cin >> a[i]; }
template<class T> T gabs(const T& x) { return max(x, -x); }
#define abs gabs

const i64 inf = 1ll << 60;
i64 n;
vector<pair<i64, i64>> ps;
int main() {
  cin >> n;
  init_n(ps, n);
  for (i64 i = 0; i < n; ++i) cin >> ps[i].first >> ps[i].second;
  
  sort(begin(ps), end(ps), [](auto p, auto q) {
    return p.second > q.second; 
  });

  vector<vector<i64>> dp(n + 1, vector<i64>(n / 3 + 1));

  for (i64 i = 1; i <= n; ++i) {
    for (i64 j = 0; j <= min(i, n / 3); ++j) {
      i64 a, b;
      tie(a, b) = ps[i - 1];
      i64 x = j < i ? dp[i - 1][j] + a + (i - j - 1) * b : inf;
      i64 y = j > 0 ? dp[i - 1][j - 1] : inf;
      dp[i][j] = min(x, y);
    }
  }

  cout << dp[n][n / 3] << endl;
  return 0;
}