L = int(input())
mod = 10 ** 9 + 7
ans = 1
for i in range(L):
    p,e = map(int,input().split())
    inv = pow(p-1,mod-2,mod)
    tmp = pow(p,e+2,mod) - p - (p-1) * (e+1)
    ans = ans * tmp * inv % mod * inv % mod
print(ans)