#include<cstdio>
#include<atcoder/modint>
using namespace atcoder;
using Mint = modint1000000007;
int main(){
    int L;
    scanf("%d", &L);
    Mint answer = Mint::raw(1);
    for (int _ = 0; _ < L; _++)
    {
        int P, E;
        scanf("%d %d", &P, &E);
        answer *= (Mint::raw(P)*(Mint::raw(P).pow(E+1) - Mint::raw(1)) - Mint::raw(P-1)*Mint::raw(E+1))/(Mint::raw(P-1).pow(2));
    }
    printf("%u\n", answer.val());
}