#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <typename T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <typename T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct IOST {
	IOST() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(20);
	}
} IOST;

using mint = atcoder::modint998244353;

void solve() {
	int n;
	cin >> n;
	vector<int> x(n), y(n);
	rep(i, 0, n) cin >> x[i] >> y[i];
	int mni = 0, mxi = 0;
	rep(i, 0, n) {
		if (x[mni] > x[i]) mni = i;
		if (x[mxi] < x[i]) mxi = i;
	}
	mint ans = 0;
	int i = mxi;
	while (i != mni) {
		int ni = (i + 1) % n;
		ans += mint(y[i] + y[ni]) * (abs(x[i] - x[ni])) / 2;
		i = ni;
	}
	while (i != mxi) {
		int ni = (i + 1) % n;
		ans -= mint(y[i] + y[ni]) * (abs(x[i] - x[ni])) / 2;
		i = ni;
	}
	cout << ans.val() << "\n";
}

int main() {
	int t = 1;
	// cin >> t;
	rep(i, 0, t) solve();
}