#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) { a = max(a, b); }
template<class T> void chmin(T& a, const T& b) { a = min(a, b); }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint1000000007;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int l;
  cin >> l;
  mint ans = 1;
  mint t = 1;
  rep(_, l) {
    int pi, e;
    cin >> pi >> e;
    mint p = pi;
    ans *= (p.pow(e + 2) - p * (e + 2) + e + 1);
    t *= (p - 1) * (p - 1);
  }
  ans /= t;
  cout << ans.val() << '\n';
}