X, Y = map(int, input().split())
N = int(input())
A = list(map(int, input().split()))

X /= 3.6
Y /= 3.6

yes = True
for i in range(N-1):
    if A[i] * Y / X > A[i+1]:
        yes = False
        break
print('YES' if yes else 'NO')