题解 | #DNA序列#
DNA序列
https://www.nowcoder.com/practice/e8480ed7501640709354db1cc4ffd42a
s=input()
n=int(input())
dic={}
for i in range(len(s)):
dic[s[i:i+n]]=(s[i:i+n].count("G")+s[i:i+n].count("C"))/n
dic=sorted(dic.items(),key=lambda v: v[1],reverse=True)
print(dic[0][0])
