x, y = map(int, input().split())
n = int(input())
a = list(map(int, input().split()))
x *= 1000
y *= 1000
x /= 3600
y /= 3600

flag = True
for i in range(n - 1):
    if (a[i] / x) * y >= a[i + 1]:
        flag = False

if flag:
    print("YES")
else:
    print("NO")