#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define REP1(i, n) for(int i=1; i<=(n); i++)
#define RREP1(i, n) for(int i=(n); i>=1; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define out(...) //printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/
#if DEBUG
#define SIZE 100
#else
#define SIZE 123450
#endif

int N;
struct Item {
    int A, B;
    Item(): A(0),B(0) {};
    Item(int A, int B): A(A), B(B) {};
};
vector<Item> M;
int size;
int maxp = -1;
int mai = -1;
int cost() {
    maxp=mai=-1;
    sort(M.begin(), M.end(), [](Item a, Item b){return a.B > b.B;});
    int c = 0;
    REP(i,size) {
        auto item = M[i];
        int p = item.A + item.B * i;
//        cout << item.A << " " << item.B << " " << p << endl;
        out(" %lld", p);
        c += p;
        if (p > maxp) {
            maxp = p;
            mai = i;
        }
    }
    out(" = %lld\n", c);
    return c;
}

void solve() {
    cin>>N;
    vector<Item> I(N);
    REP(i,N)cin>>I[i].A>>I[i].B;
    size = N/3*2 + N%3;
    REP(i,size)M.push_back(I[i]);
    int c = cost();
    FOR(i, size, N) {
        auto tmp = M;
        M[mai] = I[i];
        int n = cost();
        if (n < c) {
            // ok
            c = n;
        } else {
            // rollback
            M = tmp;
        }
    }
    cout << c << endl;
}