题解 | #DNA序列#
DNA序列
http://www.nowcoder.com/practice/e8480ed7501640709354db1cc4ffd42a
a = input().strip()
n = int(input())
l = []
m = []
for i in range(len(a)):
s = a[i:i+n].count('G') + a[i:i+n].count('C')
l.append(a[i:i+n])
m.append(s/n)
x = max(m)
print(l[m.index(x)])
