def extend_euclidean_algorithm(a, b):
    if b == 0: return 1, 0
    y, x = extend_euclidean_algorithm(b, a%b)
    y -= (a//b)*x
    return x, y
def chinese_remainder_theorem(s, p, t, q):
    d = gcd(p, q)
    if (s-t)%d: return -1, -1
    x, y = extend_euclidean_algorithm(p, q)
    return (s*q*y+t*p*x)//d, p*q//d
from math import gcd
n = int(input())
c, b = 0, 1
for _ in range(int(input())):
    bi, ci = map(int, input().split())
    c, b = chinese_remainder_theorem(c, b, ci, bi)
    if c == -1 or c > n: c = "NaN"; break
print(c)