看起来没有用split()的精妙，但效率似乎更高。

while True:
    try:
        x=int(input())
        str1=bin(x)
        count=0
        max_count=0
        for i in str1:
            if i=='1':
                count+=1
            else:
                count=0
            if count>max_count:
                max_count=count
        print(max_count)
    except:
        break