X, Y = map(int, input().split())
N = int(input())
A = list(map(int, input().split()))
A.insert(0, 0)

X /= 3.6
Y /= 3.6

for i in range(N-1):
    t = (A[i + 1] - A[i]) / X
    d = Y * t
    if d > A[i + 2] - A[i]:
        print("NO")
        break
else:
    print("YES")