x,y=map(lambda n: int(n)*1000/3600,input().split())
n=int(input())
a=[*map(int,input().split())]
X,Y=[],[]
ans='YES'
for i in range(n):
    Y.append(a[i]/y)
    X.append(a[i]/x)
    if i>=1:
        if X[i-1]>Y[i]:
            ans='NO'
            break
print(ans)