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

X = X*1000 / 3600
Y = Y*1000 / 3600

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