def safe_mod(x, m):
    x %= m
    if x < 0:
        x += m
    return x


def inv_gcd(a, b):
    a = safe_mod(a, b)
    if a == 0:
        return b, 0
    s, t = b, a
    m0, m1 = 0, 1
    while t > 0:
        u = s // t
        s -= t * u
        m0 -= m1 * u
        s, t = t, s
        m0, m1 = m1, m0
    if m0 < 0:
        m0 += b // s
    return s, m0


r,  m = 0, 1


def crt(rr, mm):
    global r, m
    r1, m1 = safe_mod(rr, mm), mm
    if m < m1:
        r, r1 = r1,  r
        m, m1 = m1, m
    if m % m1 == 0:
        if r % m1 != r1:
            r = m = 0
        return
    g, im = inv_gcd(m, m1)
    u1 = m1 // g
    if (r1 - r) % g != 0:
        r = m = 0
        return
    x = (r1 - r) // g % u1 * im % u1
    r += x * m
    m *= u1
    if r < 0:
        r += m
    return


max = int(input())
for _ in range(int(input())):
    b, c = map(int, input().split())
    crt(c, b)
    if m == 0 or r > m:
        print("NaN")
        exit()
print(r)