X,Y=map(int,input().split())
N=int(input())
A=list(map(int,input().split()))
X,Y=X/3.6,Y/3.6
for i in range(N-1):
    time=int(A[i]/X)
    if A[i+1]<(time*Y):
        print("NO")
        break
else: print("YES")