def extended_gcd(a, b):
    if b == 0:
        return a, 1, 0
    else:
        g, y, x = extended_gcd(b, a % b)
        y -= (a // b) * x
        return g, x, y


def mod_inv(a, p):
    _, x, _ = extended_gcd(a, p)
    return x % p


def pregarner(b, m, MOD):
    def gcd(a, b):
        while b:
            a, b = b, a % b
        return a

    res = 1
    n = len(b)
    for i in range(n):
        for j in range(i):
            g = gcd(m[i], m[j])
            if (b[i] - b[j]) % g != 0:
                  return -1
            m[i] //= g
            m[j] //= g
            gi = gcd(m[i], g)
            gj = g // gi

            while True:
                g = gcd(gi, gj)
                gi *= g
                gj //= g
                if g == 1:
                    break
            m[i] *= gi
            m[j] *= gj
            b[i] %= m[i]
            b[j] %= m[j]
    for i in range(n):
        res = res * m[i] % MOD
    return res


def garner(a, m, MOD):
    n = len(m)
    m = m + [MOD]
    coeff = [1] * (n + 1)
    res = [0] * (n + 1)
    for i in range(n):
        t = (a[i] - res[i]) * mod_inv(coeff[i], m[i]) % m[i]
        for j in range(i + 1, n + 1):
            res[j] = (res[j] + t * coeff[j]) % m[j]
            coeff[j] = coeff[j] * m[i] % m[j]
    return res[-1]


n = int(input())
info = [list(map(int, input().split())) for i in range(n)]
MOD = 10 ** 9 + 7

x, y = list(zip(*info))
x, y = list(x), list(y)

lcm = pregarner(x, y, MOD)
if lcm == -1:
    print(lcm)
else:
    m = garner(x, y, MOD)
    print(m)