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

d = 0
for i in range(1, N):
    t = (A[i] - A[i - 1]) / X
    d += Y * t
    if round(d, 6) > A[i + 1]:
        print("NO")
        break

else:
    print("YES")