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

# Calculate the master's arrival times at each checkpoint
sensei_times = [0.0] * (N + 1)
for i in range(1, N + 1):
    prev = A[i-2] if i >= 2 else 0
    distance = A[i-1] - prev
    time = distance / (Y * 1000)
    sensei_times[i] = sensei_times[i-1] + time

# Check each checkpoint for the losing condition
lose = False
for i in range(N - 1):
    koba_time = A[i] / (X * 1000)
    # The master's arrival time at the next checkpoint (i+2 in 0-based sensei_times)
    sensei_next_time = sensei_times[i + 2]
    if sensei_next_time < koba_time:
        lose = True
        break

print("NO" if lose else "YES")