def gcd(a, b):
    if b == 0:
        return a
    else:
        return gcd(b, a%b)

def extgcd(a, b):
    #拡張ユークリッド互除法
    #ax + by = gcd(a, b)となる(x, y)を求めます
    if b == 0:
        return [1, 0]

    q = a//b
    r = a%b
    
    s, t = extgcd(b, r)
    y = s - q*t
    return [t, y]

def lcm(a, b):
    return a // gcd(a, b) * b

def CRT(rs, ms):
    R = 0
    M = 1
    for r, m in zip(rs, ms):
        g = gcd(M, m)
        s, t = extgcd(M, m)

        if r%g != R%g:
            print(-1)
            exit(0)

        R = (m*t*R + M*s*r) // g
        M = lcm(m, M)
        R %= M
    return [R, M]

x = []
y = []
v = []
n = int(input())
for i in range(n):
    a, b = map(int, input().split())
    x.append(a)
    y.append(b)
    v.append([a, b])

r, m = CRT(x, y)

MOD = 10**9 + 7
if r == 0:
    print(m%MOD)
else:
    print(r%MOD)