题解 | #DNA序列#

while True:
    try:
        DNA_str = input()
        n = int(input())
        str1 = ''
        list1 = []
        for i in range(len(DNA_str)-n+1):
            str1 = DNA_str[i:i+n]
            n1 = str1.count('C')
            n2 = str1.count('G')
            list1.append(str(n1 + n2))
        num = max(list(map(int,list1)))
        index1 = list1.index(str(num))
        print(DNA_str[index1:index1+n])
    except:
        break