#include <iostream>
#include <atcoder/modint>
#define int long long
using namespace std;
using namespace atcoder;
using mint = modint1000000007;

// p^0 + ... + p^e
mint sum0(mint p, int e) {
	return (p.pow(e + 1) - 1) / (p - 1);
}

// 0 * p^0 + ... + e * p^e
mint sum1(mint p, int e) {
	mint res1 = p * (1 - p.pow(e)) / (p - 1) / (p - 1);
	mint res2 = e * p.pow(e + 1) / (p - 1);
	return res1 + res2;
}

signed main() {
	int L; cin >> L;
	mint ans = 1;
	while (L--) {
		int p, e; cin >> p >> e;
		ans *= sum0(p, e) * (e + 1) - sum1(p, e);
	}
	cout << ans.val() << endl;
	return 0;
}