#line 2 "/home/cocojapanpan/Procon_CPP/proconLibrary/lib/template/procon.hpp"

#ifndef DEBUG
// 提出時にassertはオフ
#ifndef NDEBUG
#define NDEBUG
#endif
// 定数倍高速化
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define ALL(x) (x).begin(), (x).end()
template <class T>
using vec = vector<T>;
template <class T, class S>
inline bool chmax(T &a, const S &b) {
    return (a < b ? a = b, 1 : 0);
}
template <class T, class S>
inline bool chmin(T &a, const S &b) {
    return (a > b ? a = b, 1 : 0);
}
template <class T>
constexpr T INF = 1'000'000'000;
template <>
constexpr int INF<int> = 1'000'000'000;
template <>
constexpr ll INF<ll> = ll(INF<int>) * INF<int> * 2;
#line 2 "main.cpp"

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vec<ll> A(N), B(N);
    ll A_sum = 0, B_sum = 0;
    for(int i = 0; i < N; i++) {
        cin >> A[i] >> B[i];
        A_sum += A[i];
        B_sum += B[i];
    }
    // 残ったAの和*Bi vs Ai*残ったBの和
    // 前者が大きいなら前におく
    vec<int> P(N);
    {
        int front = 0, back = N - 1;
        for(int i = 0; i < N - 1; i++) {
            A_sum -= A[i];
            B_sum -= B[i];
            if(A_sum * B[i] > A[i] * B_sum) {
                P[i] = front;
                ++front;
            } else {
                P[i] = back;
                --back;
            }
        }
        assert(front == back);
        P[N - 1] = front;
    }
    vec<int> inv_P(N);
    for(int i = 0; i < N; i++) {
        inv_P[P[i]] = i;
    }
    ll score = 0;
    {
        ll preB_sum = 0;
        for(int i = 1; i < N; i++) {
            preB_sum += B[inv_P[i - 1]];
            score += A[inv_P[i]] * preB_sum;
        }
    }
    cout << score << "\n";
}