#include <bits/stdc++.h>
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
const int INF=2100000000;
ll mod=1e9+7;
#define rep(i,a) for (ll i=0;i<a;i++)

//retrun x^{y}
ll my_pow(ll x,ll y){
	if(x==0) return 0;
	if(y==0) return 1;
	if(y%2) return (x*my_pow(x,y-1))%mod;
	return my_pow((x*x)%mod,y/2);
}

//  rainy ~ 雨に打たれて ~
int main() {
	int N;
	cin>>N;
	ll ans=1;
	rep(i,N){
		ll P,e;
		cin>>P>>e;
		ll rev=my_pow(P-1,mod-2);
		ll tmp=my_pow(P,e+1);
		ans*=(rev*((tmp-e-1+(((tmp-P)*rev)%mod))%mod))%mod;
		ans%=mod;
	}
	cout<<(ans+mod)%mod<<endl;
}