N = int(input())
A = list(map(int,input().split()))

dat = ["C4","D4","E4","F4","G4","A4","B4"]
l = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]

_min = 10 ** 18
ans = ""
for i in range(len(dat)):
    h = l[i]
    delta = int(N / h)
    tmp = 0
    for i in range(80):
        tmp += abs(A[i] - A[i + delta])
    if tmp < _min:
        _min = tmp
        ans = dat[i]
print(ans)