#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5 + 5, Mod = 998244353;
int n, x[N], y[N];
int f[N];

int qp(int x, int y) {
	if (y == 0)
		return 1;
	if (y % 2 == 1) {
		return x * qp(x, y - 1) % Mod;
	}
	if (y % 2 == 0) {
		int tmp = qp(x, y / 2);
		return tmp * tmp % Mod;
	}
}

signed main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> x[i] >> y[i];
	}
	//1-(x/y)
	for (int i = 1; i <= n; i++) {
		f[i] = ( (f[i - 1] + 1) % Mod * qp(((1 + Mod - (x[i] * qp(y[i], Mod - 2)) % Mod) % Mod), Mod - 2)) % Mod;
	}
	cout << f[n] << endl;
	return 0;
}