import sys
from sys import stdin
import math

N = int(stdin.readline())

A = list(map(int,stdin.readline().split()))


DF = [294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
DN = ["C4", "D4", "E4", "F4", "G4", "A4", "B4"]

S = []

for freq in DF:

    ONE = N / freq

    now = 0
    for i in range(1,N+1):
        TIME = i/N

        if TIME > ONE*50:
            now /= i-1
            break

        if (TIME // ONE) % 2 == 0:
            now += A[i-1]
        else:
            now -= A[i-1]

    S.append( abs(now) )

MI = min(S)

for i in range(6):
    if S[i] == MI:
        print (DN[i])
        break