x, y = map(int, input().split())
n = int(input())
a = list(map(int, input().split()))

x = x*10 / 36
y = y*10 / 36

for i in range(n-1):
    t = a[i] / x
    yl = t * y
    if yl > a[i+1]:
        print('NO')
        break
else:
    print('YES')