x, y = [int(i) for i in input().strip().split(" ")]
N = int(input())
A = [int(i) for i in input().strip().split(" ")]

lost = False
for i in range(N-1, 0, -1):
    X_dist = x * A[i] * 36
    if X_dist < A[i-1] * y * 36:
        lost = True
        break

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