#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
    size_t seed = hash<T>()(x.first);
    return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int INF = 1e9 + 9;
//const ll INF = 1e18 + 9;
const ll MOD = 1e9 + 7;
//const ll MOD = 998244353;
const double EPS = 1e-8;
const double PI = acos(-1);

int n;
ll a[200100];
ll b[200100];

ll solve() {
    ll sumA = 0, sumB = 0, fixA = 0, fixB = 0;
    for (int i = 0; i < n; i++) {
        sumA += a[i];
        sumB += b[i];
    }
    ll res = 0;
    for (int i = 0; i < n; i++) {
        sumA -= a[i];
        sumB -= b[i];
        const ll v0 = a[i] * fixB + b[i] * (fixA + sumA);
        const ll v1 = a[i] * (fixB + sumB) + b[i] * fixA;
        if (v0 >= v1) {
            res += v0;
            fixB += b[i];
        } else {
            res += v1;
            fixA += a[i];
        }
    }
    return res / 2;
}

void input() {
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i] >> b[i];
}

void output(const ll& res) {
    cout << res << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    const auto& res = solve();
    output(res);
}