牛牛非常怕他的女朋友，怕到了走火入魔的程度，以至于每当他看到一个字符串同时含有n,p,y三个字母他都害怕的不行。现在有一个长度为m的只包含小写字母‘a’-‘z’的字符串x，牛牛想知道能令他不害怕的最长子串的长度是多少。（对于字符串”abc”来说，”c”,”ab”都是原串的子串，但”ac”不是原串子串）


class Solution:
    def Maximumlength(self , x ):
        result=-1
        length=len(x)
        current=[]
        flag={"n":0,"p":0,'y':0}
        for i in range(length):
            current.append(x[i])
            if x[i]=="n":
                flag["n"]=flag.get("n",0)+1
            if x[i]=="p":
                flag["p"]=flag.get("p",0)+1
            if x[i] == "y":
                flag["y"]=flag.get("y",0)+1
            if flag["n"]>0 and flag["p"]>0 and flag["y"]>0:
                a=current.pop(0)
                if a == "n":
                    flag["n"] = flag.get("n", 0) - 1
                if a == "p":
                    flag["p"] = flag.get("p", 0) - 1
                if a == "y":
                    flag["y"] = flag.get("y", 0) - 1
                while flag["n"]!=0 and flag["p"]!=0 and flag["y"]!=0:
                    a=current.pop(0)
                    if a == "n":
                        flag["n"] = flag.get("n", 0) - 1
                    if a == "p":
                        flag["p"] = flag.get("p", 0) - 1
                    if a == "y":
                        flag["y"] = flag.get("y", 0) - 1


            result=max(result,len(current))

        return result