Minsu Kim/python/Rosalind / problem10

f = open('rosalind_ba1l.txt','r')
seq = f.readline().strip()
f.close

a = 0
for i in range(0, len(seq)):
    if seq[i] == 'A':
        d = 0
    if seq[i] == 'C':
        d = 1
    if seq[i] == 'G':
        d = 2
    if seq[i] == 'T':
        d = 3
    d = d*(4**(len(seq)-i-1))
    a += d
print(a)