Find a Position in a Genome Minimizing the Skew

a=input()
d={}
c,g,m=0,0,0
for i in range(len(a)):
    if a[i]=='C':
        c+=1
    elif a[i]=='G':
        g+=1
    d[i]=g-c #用字典保存每个i前缀g和c的个数差值
    if d[i]<m: #用m保存最小的i值
        m=d[i]
for key in d.keys():
    if d[key]==m:
        print(key+1,end=" ") #因为前缀的下标是从0开始的，对应到字符串上应该+1