#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'; }