import sys

def main():
    X, Y = map(int, input().split())
    N = int(input())
    A = [int(i) for i in input().split()]
    # print(X, Y, N, A)

    x_speed_per_sec_meters = (X * 1000) / 60 / 60
    y_speed_per_sec_meters = (Y * 1000) / 60 / 60
    #print("x_speed", x_speed_per_sec_meters)
    #print("y_speed", y_speed_per_sec_meters)
    for i in range(N - 1):
        # kobaがA[i]に到達時点で師匠がA[i+1]を超えていたらNO
        taken_time_sec = A[i] / x_speed_per_sec_meters
        shisyo_pos =  y_speed_per_sec_meters * taken_time_sec
        # print(taken_time_sec, shisyo_pos)
        # print("shisyo_pos:", shisyo_pos, "A[i+1]:", A[i+1])
        #if shisyo_pos > A[i+1]:
        if round(shisyo_pos,2) > A[i+1]:
            print("NO")
            sys.exit()
    print("YES")

if __name__ == '__main__':
    main()