#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)

#include <atcoder/modint>
using namespace atcoder;
using mint = modint1000000007;

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	
	int L;
	cin >> L;
	
	mint ans = 1;
	rep(i, 0, L) {
		ll pin, ein;
		cin >> pin >> ein;
		
		mint p = pin;
		mint e = ein;
		
		mint t = p.pow(ein);
		
		mint a = (e + 1) * (t*p - 1) / (p - 1);
		mint b = p * (e*t*p - (e + 1)*t + 1) / (p - 1).pow(2);
		ans *= a - b;
	}
	cout << ans.val() << '\n';
}